prof. UAM dr hab. Krzysztof Gibasiewicz

@article{Szewczyk2022b,

title = {Electron Transfer in a Bio-Photoelectrode Based on Photosystem I Multilayer Immobilized on the Conducting Glass},

author = {Sebastian Szewczyk and Alice Goyal and Mateusz Abram and Gotard Burdziński and Joanna Kargul and Krzysztof Gibasiewicz},

url = {https://doi.org/10.3390/ijms23094774},

doi = {10.3390/ijms23094774},

year  = {2022},

date = {2022-04-01},

journal = {International Journal of Molecular Sciences},

volume = {23},

number = {9},

pages = {4774},

publisher = {MDPI AG},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Goyal2022,

title = {Competition between intra-protein charge recombination and electron transfer outside photosystem I complexes used for photovoltaic applications},

author = {Alice Goyal and Sebastian Szewczyk and Gotard Burdziński and Mateusz Abram and Joanna Kargul and Krzysztof Gibasiewicz},

url = {https://doi.org/10.1007/s43630-022-00170-x},

doi = {10.1007/s43630-022-00170-x},

year  = {2022},

date = {2022-02-01},

journal = {Photochemical &$mathsemicolon$ Photobiological Sciences},

volume = {21},

number = {3},

pages = {319--336},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Sawski2021,

title = {Competition between Photoinduced Electron Transfer and Resonance Energy Transfer in an Example of Substituted Cytochrome c–Quantum Dot Systems},

author = {Jakub Sławski and Rafał Białek and Gotard Burdziński and Krzysztof Gibasiewicz and Remigiusz Worch and Joanna Grzyb},

url = {https://doi.org/10.1021/acs.jpcb.1c00325},

doi = {10.1021/acs.jpcb.1c00325},

issn = {1520-6106},

year  = {2021},

date = {2021-04-01},

journal = {The Journal of Physical Chemistry B},

volume = {125},

number = {13},

pages = {3307--3320},

publisher = {American Chemical Society (ACS)},

abstract = {Colloidal quantum dots (QDs) are nanoparticles that are able to photoreduce redox proteins by electron transfer (ET). QDs are also able to transfer energy by resonance energy transfer (RET). Here, we address the question of the competition between these two routes of QDs' excitation quenching, using cadmium telluride QDs and cytochrome c (CytC) or its metal-substituted derivatives. We used both oxidized and reduced versions of native CytC, as well as fluorescent, nonreducible Zn(II)CytC, Sn(II)CytC, and metal-free porphyrin CytC. We found that all of the CytC versions quench QD fluorescence, although the interaction may be described differently in terms of static and dynamic quenching. QDs may be quenchers of fluorescent CytC derivatives, with significant differences in effectiveness depending on QD size. SnCytC and porphyrin CytC increased the rate of Fe(III)CytC photoreduction, and Fe(II)CytC slightly decreased the rate and ZnCytC presence significantly decreased the rate and final level of reduced FeCytC. These might be partially explained by the tendency to form a stable complex between protein and QDs, which promoted RET and collisional quenching. Our findings show that there is a net preference for photoinduced ET over other ways of energy transfer, at least partially, due to a lack of donors, regenerating a hole at QDs and leading to irreversibility of ET events. There may also be a common part of pathways leading to photoinduced ET and RET. The nature of synergistic action observed in some cases allows the hypothesis that RET may be an additional way to power up the ET.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Dubas2021,

title = {Antagonistic Effects of Point Mutations on Charge Recombination and a New View of Primary Charge Separation in Photosynthetic Proteins},

author = {Katarzyna Dubas and Sebastian Szewczyk and Rafał Białek and G Burdziński and M R Jones and Krzysztof Gibasiewicz},

url = {https://doi.org/10.1021/acs.jpcb.1c03978},

doi = {10.1021/acs.jpcb.1c03978},

year  = {2021},

date = {2021-01-01},

journal = {The Journal of Physical Chemistry B},

volume = {125},

number = {31},

pages = {8742--8756},

publisher = {American Chemical Society (ACS)},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2021,

title = {Temperature dependence of nanosecond charge recombination in mutant Rhodobacter sphaeroides reaction centers: modelling of the protein dynamics},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and Rafał Białek and Michael R Jones},

url = {https://doi.org/10.1007/s43630-021-00069-z},

doi = {10.1007/s43630-021-00069-z},

year  = {2021},

date = {2021-01-01},

journal = {Photochemical & Photobiological Sciences},

volume = {20},

number = {7},

pages = {913--922},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Szewczyk2020,

title = {On the nature of uncoupled chlorophylls in the extremophilic photosystem I-light harvesting I supercomplex},

author = {Sebastian Szewczyk and Mateusz Abram and Rafał Białek and Patrycja Haniewicz and Jerzy Karolczak and Jacek Gapiński and Joanna Kargul and Krzysztof Gibasiewicz},

url = {https://linkinghub.elsevier.com/retrieve/pii/S0005272819301902},

doi = {10.1016/j.bbabio.2019.148136},

issn = {00052728},

year  = {2020},

date = {2020-02-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1861},

number = {2},

pages = {148136},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Szewczyk2020b,

title = {Excitation dynamics in Photosystem I trapped in TiO2 mesopores},

author = {Sebastian Szewczyk and Rafał Białek and Wojciech Giera and G Burdziński and Rienk van Grondelle and Krzysztof Gibasiewicz},

url = {https://doi.org/10.1007/s11120-020-00730-1 http://link.springer.com/10.1007/s11120-020-00730-1},

doi = {10.1007/s11120-020-00730-1},

issn = {0166-8595},

year  = {2020},

date = {2020-02-01},

journal = {Photosynthesis Research},

number = {0123456789},

publisher = {Springer Netherlands},

abstract = {Excitation decay in closed Photosystem I (PSI) isolated from cyanobacterium Synechocystis sp. PCC 6803 and dissolved in a buffer solution occurs predominantly with a ~ 24-ps lifetime, as measured both by time-resolved fluorescence and transient absorption. The same PSI particles deposited in mesoporous matrix made of TiO2 nanoparticles exhibit significantly accelerated excitation decay dominated by a ~ 6-ps component. Target analysis indicates that this acceleration is caused by ~ 50% increase of the rate constant of bulk Chls excitation quenching. As an effect of this increase, as much as ~ 70% of bulk Chls excitation is quenched before the establishment of equilibrium with the red Chls. Accelerated quenching may be caused by increased excitation trapping by the reaction center and/or quenching properties of the TiO2 surface directly interacting with PSI Chls. Also properties of the PSI red Chls are affected by the deposition in the TiO2 matrix: they become deeper traps due to an increase of their number and their oscillator strength is significantly reduced. These effects should be taken into account when constructing solar cells' photoelectrodes composed of PSI and artificial matrices.},

keywords = {Excitation dynamics, Photosystem I, Primary charge separation, Synechocystis, Target analysis, Time-resolved fluorescence, Transient absorption},

pubstate = {published},

tppubtype = {article}

}

@article{Szewczyk2020c,

title = {Photovoltaic activity of electrodes based on intact photosystem I electrodeposited on bare conducting glass},

author = {Sebastian Szewczyk and Rafał Białek and Gotard Burdziński and Krzysztof Gibasiewicz},

url = {https://doi.org/10.1007/s11120-020-00722-1 http://link.springer.com/10.1007/s11120-020-00722-1},

doi = {10.1007/s11120-020-00722-1},

issn = {0166-8595},

year  = {2020},

date = {2020-02-01},

journal = {Photosynthesis Research},

number = {0123456789},

publisher = {Springer Netherlands},

keywords = {cyanobacterium synechocystis sp, Cyanobacterium Synechocystis sp. PCC 6803, Femtosecond-transient absorption, FTO conducting glass, pcc 6803, Photoelectrochemical measurements, Photosystem I, Photovoltaics},

pubstate = {published},

tppubtype = {article}

}

@article{Abram2020,

title = {Remodeling of excitation energy transfer in extremophilic red algal PSI-LHCI complex during light adaptation},

author = {Mateusz Abram and Rafał Białek and Sebastian Szewczyk and Jerzy Karolczak and Krzysztof Gibasiewicz and Joanna Kargul},

url = {https://linkinghub.elsevier.com/retrieve/pii/S0005272819301409},

doi = {10.1016/j.bbabio.2019.148093},

issn = {00052728},

year  = {2020},

date = {2020-01-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1861},

number = {1},

pages = {148093},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Biaek2020,

title = {In situ spectroelectrochemical investigation of a biophotoelectrode based on photoreaction centers embedded in a redox hydrogel},

author = {Rafał Białek and Vincent Friebe and Adrian Ruff and Michael R Jones and Raoul Frese and Krzysztof Gibasiewicz},

url = {https://linkinghub.elsevier.com/retrieve/pii/S0013468619320614},

doi = {10.1016/j.electacta.2019.135190},

issn = {00134686},

year  = {2020},

date = {2020-01-01},

journal = {Electrochimica Acta},

volume = {330},

pages = {135190},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.jpcb.0c08714,

title = {Insight into Electron Transfer from a Redox Polymer to a Photoactive Protein},

author = {Rafał Białek and Kalyani Thakur and Adrian Ruff and Michael R Jones and Wolfgang Schuhmann and Charusheela Ramanan and Krzysztof Gibasiewicz},

url = {https://doi.org/10.1021/acs.jpcb.0c08714},

doi = {10.1021/acs.jpcb.0c08714},

year  = {2020},

date = {2020-01-01},

journal = {The Journal of Physical Chemistry B},

volume = {124},

number = {49},

pages = {11123-11132},

abstract = {Biohybrid photoelectrochemical systems in photovoltaic or biosensor applications have gained considerable attention in recent years. While the photoactive proteins engaged in such systems usually maintain an internal charge separation quantum yield of nearly 100%, the subsequent steps of electron and hole transfer beyond the protein often limit the overall system efficiency and their kinetics remain largely uncharacterized. To reveal the dynamics of one of such charge-transfer reactions, we report on the reduction of Rhodobacter sphaeroides reaction centers (RCs) by Os-complex-modified redox polymers (P-Os) characterized using transient absorption spectroscopy. RCs and P-Os were mixed in buffered solution in different molar ratios in the presence of a water-soluble quinone as an electron acceptor. Electron transfer from P-Os to the photoexcited RCs could be described by a three-exponential function, the fastest lifetime of which was on the order of a few microseconds, which is a few orders of magnitude faster than the internal charge recombination of RCs with fully separated charge. This was similar to the lifetime for the reduction of RCs by their natural electron donor, cytochrome c2. The rate of electron donation increased with increasing ratio of polymer to protein concentrations. It is proposed that P-Os and RCs engage in electrostatic interactions to form complexes, the sizes of which depend on the polymer-to-protein ratio. Our findings throw light on the processes within hydrogel-based biophotovoltaic devices and will inform the future design of materials optimally suited for this application.},

note = {PMID: 33236901},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Szewczyk2018b,

title = {Acceleration of the excitation decay in Photosystem I immobilized on glass surface},

author = {Sebastian Szewczyk and Wojciech Giera and Rafał Białek and Gotard Burdziński and Krzysztof Gibasiewicz},

url = {http://link.springer.com/10.1007/s11120-017-0454-z},

doi = {10.1007/s11120-017-0454-z},

issn = {0166-8595},

year  = {2018},

date = {2018-05-01},

journal = {Photosynthesis Research},

volume = {136},

number = {2},

pages = {171-181},

abstract = {textcopyright 2017 The Author(s) Femtosecond transient absorption was used to study excitation decay in monomeric and trimeric cyanobacterial Photosystem I (PSI) being prepared in three states: (1) in aqueous solution, (2) deposited and dried on glass surface (either conducting or non-conducting), and (3) deposited on glass (conducting) surface but being in contact with aqueous solvent. The main goal of this contribution was to determine the reason of the acceleration of the excitation decay in dried PSI deposited on the conducting surface relative to PSI in solution observed previously using time-resolved fluorescence (Szewczyk et al., Photysnth Res 132(2):111–126, 2017). We formulated two alternative working hypotheses: (1) the acceleration results from electron injection from PSI to the conducting surface; (2) the acceleration is caused by dehydration and/or crowding of PSI proteins deposited on the glass substrate. Excitation dynamics of PSI in all three types of samples can be described by three main components of subpicosecond, 3–5, and 20–26 ps lifetimes of different relative contributions in solution than in PSI-substrate systems. The presence of similar kinetic components for all the samples indicates intactness of PSI proteins after their deposition onto the substrates. The kinetic traces for all systems with PSI deposited on substrates are almost identical and they decay significantly faster than the kinetic traces of PSI in solution. We conclude that the accelerated excitation decay in PSI-substrate systems is caused mostly by dense packing of proteins.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Biaek2018,

title = {Modelling of the cathodic and anodic photocurrents from Rhodobacter sphaeroides reaction centres immobilized on titanium dioxide},

author = {Rafał Białek and David J K Swainsbury and Maciej Wiesner and Michael R Jones and Krzysztof Gibasiewicz},

url = {http://link.springer.com/10.1007/s11120-018-0550-8},

doi = {10.1007/s11120-018-0550-8},

issn = {0166-8595},

year  = {2018},

date = {2018-01-01},

journal = {Photosynthesis Research},

volume = {0},

number = {0},

pages = {0},

publisher = {Springer Netherlands},

keywords = {Purple bacteria},

pubstate = {published},

tppubtype = {article}

}

@article{Giera2018,

title = {Uphill energy transfer in photosystem I from Chlamydomonas reinhardtii. Time-resolved fluorescence measurements at 77 K},

author = {Wojciech Giera and Sebastian Szewczyk and Michael D McConnell and Kevin E Redding and Rienk van Grondelle and Krzysztof Gibasiewicz},

url = {https://doi.org/10.1007/s11120-018-0506-z},

doi = {10.1007/s11120-018-0506-z},

issn = {1573-5079},

year  = {2018},

date = {2018-01-01},

journal = {Photosynthesis Research},

volume = {137},

number = {2},

pages = {321-335},

abstract = {Energetic properties of chlorophylls in photosynthetic complexes are strongly modulated by their interaction with the protein matrix and by inter-pigment coupling. This spectral tuning is especially striking in photosystem I (PSI) complexes that contain low-energy chlorophylls emitting above 700 nm. Such low-energy chlorophylls have been observed in cyanobacterial PSI, algal and plant PSI--LHCI complexes, and individual light-harvesting complex I (LHCI) proteins. However, there has been no direct evidence of their presence in algal PSI core complexes lacking LHCI. In order to determine the lowest-energy states of chlorophylls and their dynamics in algal PSI antenna systems, we performed time-resolved fluorescence measurements at 77 K for PSI core and PSI--LHCI complexes isolated from the green alga Chlamydomonas reinhardtii. The pool of low-energy chlorophylls observed in PSI cores is generally smaller and less red-shifted than that observed in PSI--LHCI complexes. Excitation energy equilibration between bulk and low-energy chlorophylls in the PSI--LHCI complexes at 77 K leads to population of excited states that are less red-shifted (by textasciitildethinspace12 nm) than at room temperature. On the other hand, analysis of the detection wavelength dependence of the effective trapping time of bulk excitations in the PSI core at 77 K provided evidence for an energy threshold at textasciitildethinspace675 nm, above which trapping slows down. Based on these observations, we postulate that excitation energy transfer from bulk to low-energy chlorophylls and from bulk to reaction center chlorophylls are thermally activated uphill processes that likely occur via higher excitonic states of energy accepting chlorophylls.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Szewczyk2017b,

title = {Comparison of excitation energy transfer in cyanobacterial photosystem I in solution and immobilized on conducting glass},

author = {Sebastian Szewczyk and Wojciech Giera and Sandrine D'Haene and Rienk van Grondelle and Krzysztof Gibasiewicz},

url = {http://link.springer.com/10.1007/s11120-016-0312-4},

doi = {10.1007/s11120-016-0312-4},

issn = {0166-8595},

year  = {2017},

date = {2017-05-01},

journal = {Photosynthesis Research},

volume = {132},

number = {2},

pages = {111--126},

publisher = {Springer Netherlands},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Biaek2016,

title = {Bacteriopheophytin triplet state in Rhodobacter sphaeroides reaction centers},

author = {Rafał Białek and Gotard Burdziński and Michael R Jones and Krzysztof Gibasiewicz},

url = {http://link.springer.com/10.1007/s11120-016-0290-6},

doi = {10.1007/s11120-016-0290-6},

issn = {0166-8595},

year  = {2016},

date = {2016-08-01},

journal = {Photosynthesis Research},

volume = {129},

number = {2},

pages = {205--216},

publisher = {Springer Netherlands},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2016,

title = {Weak temperature dependence of P + H A − recombination in mutant Rhodobacter sphaeroides reaction centers},

author = {Krzysztof Gibasiewicz and Rafał Białek and Maria Pajzderska and Jerzy Karolczak and Gotard Burdziński and Michael R Jones and Klaus Brettel},

url = {http://www.ncbi.nlm.nih.gov/pubmed/26942583 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC4877430 http://link.springer.com/10.1007/s11120-016-0239-9},

doi = {10.1007/s11120-016-0239-9},

issn = {0166-8595},

year  = {2016},

date = {2016-06-01},

journal = {Photosynthesis Research},

volume = {128},

number = {3},

pages = {243--258},

abstract = {In contrast with findings on the wild-type Rhodobacter sphaeroides reaction center, biexponential P (+) H A (-) → PH A charge recombination is shown to be weakly dependent on temperature between 78 and 298 K in three variants with single amino acids exchanged in the vicinity of primary electron acceptors. These mutated reaction centers have diverse overall kinetics of charge recombination, spanning an average lifetime from ~2 to ~20 ns. Despite these differences a protein relaxation model applied previously to wild-type reaction centers was successfully used to relate the observed kinetics to the temporal evolution of the free energy level of the state P (+) H A (-) relative to P (+) B A (-) . We conclude that the observed variety in the kinetics of charge recombination, together with their weak temperature dependence, is caused by a combination of factors that are each affected to a different extent by the point mutations in a particular mutant complex. These are as follows: (1) the initial free energy gap between the states P (+) B A (-) and P (+) H A (-) , (2) the intrinsic rate of P (+) B A (-) → PB A charge recombination, and (3) the rate of protein relaxation in response to the appearance of the charge separated states. In the case of a mutant which displays rapid P (+) H A (-) recombination (ELL), most of this recombination occurs in an unrelaxed protein in which P (+) B A (-) and P (+) H A (-) are almost isoenergetic. In contrast, in a mutant in which P (+) H A (-) recombination is relatively slow (GML), most of the recombination occurs in a relaxed protein in which P (+) H A (-) is much lower in energy than P (+) H A (-) . The weak temperature dependence in the ELL reaction center and a YLH mutant was modeled in two ways: (1) by assuming that the initial P (+) B A (-) and P (+) H A (-) states in an unrelaxed protein are isoenergetic, whereas the final free energy gap between these states following the protein relaxation is large (~250 meV or more), independent of temperature and (2) by assuming that the initial and final free energy gaps between P (+) B A (-) and P (+) H A (-) are moderate and temperature dependent. In the case of the GML mutant, it was concluded that the free energy gap between P (+) B A (-) and P (+) H A (-) is large at all times.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Dubas2016,

title = {Unified Model of Nanosecond Charge Recombination in Closed Reaction Centers from Rhodobacter sphaeroides : Role of Protein Polarization Dynamics},

author = {Katarzyna Dubas and M Baranowski and A Podhorodecki and M R Jones and Krzysztof Gibasiewicz},

url = {http://pubs.acs.org/doi/10.1021/acs.jpcb.6b01459},

doi = {10.1021/acs.jpcb.6b01459},

issn = {1520-6106},

year  = {2016},

date = {2016-06-01},

journal = {The Journal of Physical Chemistry B},

volume = {120},

number = {22},

pages = {4890--4896},

publisher = {American Chemical Society},

abstract = {Ongoing questions surround the influence of protein dynamics on rapid processes such as biological electron transfer. Such questions are particularly addressable in light-activated systems. In Rhodobacter sphaeroides reaction centers, charge recombination or back electron transfer from the reduced bacteriopheophytin, HA–, to the oxidized dimeric bacteriochlorophyll, P+, may be monitored by both transient absorption spectroscopy and transient fluorescence spectroscopy. Signals measured with both these techniques decay in a similar three-exponential fashion with lifetimes of ∼0.6–0.7, ∼2–4, and ∼10–20 ns, revealing the complex character of this electron transfer reaction. In this study a single kinetic model was developed to connect lifetime and amplitude data from both techniques. The model took into account the possibility that electron transfer from HA– to P+ may occur with transient formation of the state P+BA–. As a result it was possible to model the impact of nanosecond protein relaxation on the free...},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Adamiec2015,

title = {Excitation energy transfer and charge separation are affected in Arabidopsis thaliana mutants lacking light-harvesting chlorophyll a/b binding protein Lhcb3},

author = {Małgorzata Adamiec and Krzysztof Gibasiewicz and Robert Luciński and Wojciech Giera and Przemysław Chełminiak and Sebastian Szewczyk and Weronika Sipińska and Rienk van Grondelle and Grzegorz Jackowski},

url = {http://www.ncbi.nlm.nih.gov/pubmed/26562806 http://linkinghub.elsevier.com/retrieve/pii/S1011134415003619},

doi = {10.1016/j.jphotobiol.2015.11.002},

issn = {10111344},

year  = {2015},

date = {2015-12-01},

journal = {Journal of Photochemistry and Photobiology B: Biology},

volume = {153},

pages = {423--428},

abstract = {The composition of LHCII trimers as well as excitation energy transfer and charge separation in grana cores of Arabidopsis thaliana mutant lacking chlorophyll a/b binding protein Lhcb3 have been investigated and compared to those in wild-type plants. In grana cores of lhcb3 plants we observed increased amounts of Lhcb1 and Lhcb2 apoproteins per PSII core. The additional copies of Lhcb1 and Lhcb2 are expected to substitute for Lhcb3 in LHCII trimers M as well as in the LHCII "extra" pool, which was found to be modestly enlarged as a result of the absence of Lhcb3. Time-resolved fluorescence measurements reveal a deceleration of the fast phase of excitation dynamics in grana cores of the mutant by ~15 ps, whereas the average fluorescence lifetime is not significantly altered. Monte Carlo modeling predicts a slowing down of the mean hopping time and an increased stabilization of the primary charge separation in the mutant. Thus our data imply that absence of apoprotein Lhcb3 results in detectable differences in excitation energy transfer and charge separation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2015,

title = {Monte Carlo simulations of excitation and electron transfer in grana membranes},

author = {Krzysztof Gibasiewicz and Małgorzata Adamiec and Robert Luciński and Wojciech Giera and Przemysław Chełminiak and Sebastian Szewczyk and Weronika Sipińska and Edyta Głów and Jerzy Karolczak and Rienk van Grondelle and Grzegorz Jackowski},

url = {http://www.ncbi.nlm.nih.gov/pubmed/25524819 http://linkinghub.elsevier.com/retrieve/pii/S0005272814006628},

doi = {10.1016/j.bbabio.2014.12.004},

issn = {00052728},

year  = {2015},

date = {2015-03-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1847},

number = {3},

pages = {314--327},

abstract = {Time-resolved fluorescence measurements on grana membranes with instrumental response function of 3 ps reveal faster excitation dynamics (120 ps) than those reported previously. A possible reason for the faster decay may be a relatively low amount of "extra" LHCII trimers per reaction center of Photosystem II. Monte Carlo modeling of excitation dynamics in C2S2M2 form of PSII-LHCII supercomplexes has been performed using a coarse grained model of this complex, constituting a large majority of proteins in grana membranes. The main factor responsible for the fast fluorescence decay reported in this work was the deep trap constituted by the primary charge separated state in the reaction center (950-1090 cm(-1)). This value is critical for a good fit, whereas typical hopping times between antenna polypeptides (from ~4.5 to ~10.5 ps) and reversible primary charge separation times (from ~4 to ~1.5 ps, respectively) are less critical. Consequently, respective mean migration times of excitation from anywhere in the PSII-LHCII supercomplexes to reaction center range from ~30 to ~80 ps. Thus 1/4-2/3 of the ~120-ps average excitation lifetime is necessary for the diffusion of excitation to reaction center, whereas the remaining time is due to the bottle-neck effect of the trap. Removal of 27% of the Lhcb6 apoprotein pool by mutagenesis of DEG5 gene caused the acceleration of the excitation decay from ~120 to ~100 ps. This effect may be due to the detachment of LHCII-M trimers from PSII-LHCII supercomplexes, accompanied by deepening of the reaction center trap.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Giera2014,

title = {Excitation dynamics in Photosystem I from Chlamydomonas reinhardtii. Comparative studies of isolated complexes and whole cells},

author = {Wojciech Giera and Sebastian Szewczyk and Michael D McConnell and Joris Snellenburg and Kevin E Redding and Rienk van Grondelle and Krzysztof Gibasiewicz},

url = {http://www.ncbi.nlm.nih.gov/pubmed/24973599 http://linkinghub.elsevier.com/retrieve/pii/S0005272814005192},

doi = {10.1016/j.bbabio.2014.06.004},

issn = {00052728},

year  = {2014},

date = {2014-10-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1837},

number = {10},

pages = {1756--1768},

abstract = {Identical time-resolved fluorescence measurements with ~3.5-ps resolution were performed for three types of PSI preparations from the green alga, Chlamydomonas reinhardtii: isolated PSI cores, isolated PSI-LHCI complexes and PSI-LHCI complexes in whole living cells. Fluorescence decay in these types of PSI preparations has been previously investigated but never under the same experimental conditions. As a result we present consistent picture of excitation dynamics in algal PSI. Temporal evolution of fluorescence spectra can be generally described by three decay components with similar lifetimes in all samples (6-8ps, 25-30ps, 166-314ps). In the PSI cores, the fluorescence decay is dominated by the two fastest components (~90%), which can be assigned to excitation energy trapping in the reaction center by reversible primary charge separation. Excitation dynamics in the PSI-LHCI preparations is more complex because of the energy transfer between the LHCI antenna system and the core. The average trapping time of excitations created in the well coupled LHCI antenna system is about 12-15ps longer than excitations formed in the PSI core antenna. Excitation dynamics in PSI-LHCI complexes in whole living cells is very similar to that observed in isolated complexes. Our data support the view that chlorophylls responsible for the long-wavelength emission are located mostly in LHCI. We also compared in detail our results with the literature data obtained for plant PSI.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2013a,

title = {Analysis of the temperature-dependence of P+HA− charge recombination in the Rhodobacter sphaeroides reaction center suggests nanosecond temperature-independent protein relaxation},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and Andrzej Dobek and Jerzy Karolczak and Gotard Burdziński and Klaus Brettel and Michael R Jones},

url = {http://www.ncbi.nlm.nih.gov/pubmed/23999896 http://xlink.rsc.org/?DOI=c3cp44187c},

doi = {10.1039/c3cp44187c},

issn = {1463-9076},

year  = {2013},

date = {2013-10-01},

journal = {Physical Chemistry Chemical Physics},

volume = {15},

number = {38},

pages = {16321-16333},

abstract = {The temperature dependence of charge recombination of the pair P(+)HA(-) in isolated reaction centers from the purple bacterium Rhodobacter sphaeroides with prereduced quinone QA was studied by sub-nanosecond to microsecond time-scale transient absorption. Overall, the kinetics slowed down substantially upon cooling from room temperature to ∼200 K, and then remained virtually unchanged down to 77 K, indicating the coexistence of two competitive pathways of charge recombination, a thermally-activated pathway appearing only above ~200 K and a temperature-independent pathway. In our modelling, the thermally activated pathway includes an uphill electron transfer from HA(-) to BA(-) leading to transient formation of the state P(+)BA(-), whereas the temperature-independent pathway is due to direct downhill electron transfer from HA(-) to P(+). At all temperatures studied, the kinetics could be approximated by a four-component decay. Detailed analysis of the lifetimes and amplitudes of particular phases over the range of temperatures suggests that the kinetically resolved phases reveal the consecutive appearance of three conformational states characterized by an increasing free energy gap between the states P(+)BA(-) and P(+)HA(-). The initial gap between these states was estimated to be only ~8 meV, the intermediate gap being ~92 meV, and the final gap ~135 meV, with no dependence on temperature. It was also calculated through a very straightforward approach that the relaxation process from the initial to the intermediate state occurs within 0.6 ± 0.1 ns, whereas the second step of relaxation from the intermediate to the final state takes 11 ± 2 ns. Both phases of the protein relaxation process are essentially temperature-independent. Possible alternative models to describe the experimental data that cannot be definitely excluded are also discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2013b,

title = {Analysis of the Kinetics of P + H A – Recombination in Membrane-Embedded Wild-Type and Mutant Rhodobacter sphaeroides Reaction Centers between 298 and 77 K Indicates That the Adjacent Negatively Charged Q A Ubiquinone Modulates the Free Energy of P + H A},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and Andrzej Dobek and Klaus Brettel and Michael R Jones},

url = {http://pubs.acs.org/doi/10.1021/jp4011235},

doi = {10.1021/jp4011235},

issn = {1520-6106},

year  = {2013},

date = {2013-09-01},

journal = {The Journal of Physical Chemistry B},

volume = {117},

number = {38},

pages = {11112--11123},

publisher = {American Chemical Society},

abstract = {Time-resolved spectroscopic studies of recombination of the P+HA– radical pair in photosynthetic reaction centers (RCs) from Rhodobacter sphaeroides give an opportunity to study protein dynamics triggered by light and occurring over the lifetime of P+HA–. The state P+HA– is formed after the ultrafast light-induced electron transfer from the primary donor pair of bacteriochlorophylls (P) to the acceptor bacteriopheophytin (HA). In order to increase the lifetime of this state, and thus increase the temporal window for the examination of protein dynamics, it is possible to block forward electron transfer from HA– to the secondary electron acceptor QA. In this contribution, the dynamics of P+HA– recombination were compared at a range of temperatures from 77 K to room temperature, electron transfer from HA– to QA being blocked either by prereduction of QA or by genetic removal of QA. The observed P+HA– charge recombination was significantly slower in the QA-deficient RCs, and in both types of complexes, loweri...},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2012,

title = {Primary electron transfer reactions in membrane-bound open and closed reaction centers from purple bacterium Rhodobacter sphaeroides},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and Jerzy Karolczak and Gotard Burdziński and Andrzej Dobek and Michael R Jones},

doi = {10.12693/APhysPolA.122.263},

year  = {2012},

date = {2012-01-01},

journal = {Acta Physica Polonica A},

volume = {131},

number = {2},

pages = {263-268},

abstract = {Most ultrafast transient absorption studies of primary electron transfer in reaction centers from purple bacteria have been performed in complexes isolated from their natural lipid membrane environment using detergent. In this contribution we present near-UV-vis transient absorption studies of reaction centers embedded in their natural membrane environment. The evolution of absorption spectra recorded with subpicosecond resolution and reflecting primarily electron transfer reactions has been compared to data obtained previously for isolated reaction centers. We conclude that the overall spectral evolution in both types of samples is similar, and the environment of the reaction center protein has only a minor effect on the primary electron transfer reactions. The differences between the two samples are explained in terms of different energetic levels (and their different temporal evolution) of the two initial charge separated states P+BA- and P+HA-, with P being the primary electron donor and BA and HA the two consecutive electron acceptors. Additionally, in the electric field generated by P+HA-, BA in membrane-bound reaction centers undergoes a stronger electrochromic shift than in isolated reaction centers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2011,

title = {Mechanism of Recombination of the P + H A – Radical Pair in Mutant Rhodobacter sphaeroides Reaction Centers with Modified Free Energy Gaps Between P + B A – and P + H A –},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and Jane A Potter and Paul. K Fyfe and Andrzej Dobek and Klaus Brettel and Michael R Jones},

url = {http://pubs.acs.org/doi/abs/10.1021/jp206462g},

doi = {10.1021/jp206462g},

issn = {1520-6106},

year  = {2011},

date = {2011-11-01},

journal = {The Journal of Physical Chemistry B},

volume = {115},

number = {44},

pages = {13037--13050},

publisher = {American Chemical Society},

abstract = {The kinetics of recombination of the P+HA– radical pair were compared in wild-type reaction centers from Rhodobacter sphaeroides and in seven mutants in which the free energy gap, $Delta$G, between the charge separated states P+BA– and P+HA– was either increased or decreased. Five of the mutant RCs had been described previously, and X-ray crystal structures of two newly constructed complexes were determined by X-ray crystallography. The charge recombination reaction was accelerated in all mutants with a smaller $Delta$G than in the wild-type, and was slowed in a mutant having a larger $Delta$G. The free energy difference between the state P+HA– and the PHA ground state was unaffected by most of these mutations. These observations were consistent with a model in which the P+HA– → PHA charge recombination is thermally activated and occurs via the intermediate state P+BA–, with a mean rate related to the size of the $Delta$G between the states P+BA– and P+HA– and not the $Delta$G between P+HA– and the ground state. A more detailed analys...},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Giera2010,

title = {Effect of the P700 pre-oxidation and point mutations near A0 on the reversibility of the primary charge separation in Photosystem I from Chlamydomonas reinhardtii},

author = {Wojciech Giera and V M Ramesh and Andrew N Webber and Ivo van Stokkum and Rienk van Grondelle and Krzysztof Gibasiewicz},

url = {https://www.sciencedirect.com/science/article/pii/S000527280900262X http://linkinghub.elsevier.com/retrieve/pii/S000527280900262X},

doi = {10.1016/j.bbabio.2009.09.006},

issn = {00052728},

year  = {2010},

date = {2010-01-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1797},

number = {1},

pages = {106--112},

publisher = {Elsevier},

abstract = {Time-resolved fluorescence studies with a 3-ps temporal resolution were performed in order to: (1) test the recent model of the reversible primary charge separation in Photosystem I (Muller et al., 2003; Holwzwarth et al., 2005, 2006), and (2) to reconcile this model with a mechanism of excitation energy quenching by closed Photosystem I (with P700 pre-oxidized to P700+). For these purposes, we performed experiments using Photosystem I core samples isolated from Chlamydomonas reinhardtii wild type, and two mutants in which the methionine axial ligand to primary electron acceptor, A0, has been change to either histidine or serine. The temporal evolution of fluorescence spectra was recorded for each preparation under conditions where the “primary electron donor,” P700, was either neutral or chemically pre-oxidized to P700+. For all the preparations under study, and under neutral and oxidizing conditions, we observed multiexponential fluorescence decay with the major phases of ∼7 ps and ∼25 ps. The relative amplitudes and, to a minor extent the lifetimes, of these two phases were modulated by the redox state of P700 and by the mutations near A0: both pre-oxidation of P700 and mutations caused slight deceleration of the excited state decay. These results are consistent with a model in which P700 is not the primary electron donor, but rather a secondary electron donor, with the primary charge separation event occurring between the accessory chlorophyll, A, and A0. We assign the faster phase to the equilibration process between the excited state of the antenna/reaction center ensemble and the primary radical pair, and the slower phase to the secondary electron transfer reaction. The pre-oxidation of P700 shifts the equilibrium between the excited state and the primary radical pair towards the excited state. This shift is proposed to be induced by the presence of the positive charge on P700+. The same charge is proposed to be responsible for the fast A+A0−→AA0 charge recombination to the ground state and, in consequence, excitation quenching in closed reaction centers. Mutations of the A0 axial ligand shift the equilibrium in the same direction as pre-oxidation of P700 due to the up-shift of the free energy level of the state A+A0−.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2009,

title = {Excitation and electron transfer in reaction centers from Rhodobacter sphaeroides probed and analyzed globally in the 1-nanosecond temporal window from 330 to 700 nm},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and J Karolczak and Andrzej Dobek},

url = {http://xlink.rsc.org/?DOI=b912431d},

doi = {10.1039/b912431d},

issn = {1463-9076},

year  = {2009},

date = {2009-11-01},

journal = {Physical Chemistry Chemical Physics},

volume = {11},

number = {44},

pages = {10484},

publisher = {The Royal Society of Chemistry},

abstract = {Global analysis of a set of room temperature transient absorption spectra of Rhodobacter sphaeroidesreaction centers, recorded in wide temporal and spectral ranges and triggered by femtosecond excitation of accessory bacteriochlorophylls at 800 nm, is presented. The data give a comprehensive review of all spectral dynamics features in the visible and near UV, from 330 to 700 nm, related to the primary events in the Rb. sphaeroidesreaction center: excitation energy transfer from the accessory bacteriochlorophylls (B) to the primary donor (P), primary charge separation between the primary donor and primary acceptor (bacteriopheophytin, H), and electron transfer from the primary to the secondary electron acceptor (ubiquinone). In particular, engagement of the accessory bacteriochlorophyll in primary charge separation is shown as an intermediate electron acceptor, and the initial free energy gap of ∼40 meV, between the states P+BA− and P+HA− is estimated. The size of this gap is shown to be constant for the whole 230 ps lifetime of the P+HA− state. The ultrafast spectral dynamics features recorded in the visible range are presented against a background of results from similar studies performed for the last two decades.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2009b,

title = {Internal Electrostatic Control of the Primary Charge Separation and Recombination in Reaction Centers from Rhodobacter sphaeroides Revealed by Femtosecond Transient Absorption},

author = {Krzysztof Gibasiewicz and Maria Pajzderska and M Ziółek and J Karolczak and Andrzej Dobek},

url = {http://pubs.acs.org/doi/abs/10.1021/jp811234q},

doi = {10.1021/jp811234q},

issn = {1520-6106},

year  = {2009},

date = {2009-08-01},

journal = {The Journal of Physical Chemistry B},

volume = {113},

number = {31},

pages = {11023--11031},

publisher = {American Chemical Society},

abstract = {We report the observation of two conformational states of closed RCs from Rhodobacter sphaeroides characterized by different P+HA− → PHA charge recombination lifetimes, one of which is of subnanosecond value (700 ± 200 ps). These states are also characterized by different primary charge separation lifetimes. It is proposed that the distinct conformations are related to two protonation states either of reduced secondary electron acceptor, QA−, or of a titratable amino acid residue localized near QA. The reaction centers in the protonated state are characterized by faster charge separation and slower charge recombination when compared to those in the unprotonated state. Both effects are explained in terms of the model assuming modulation of the free energy level of the state P+HA− by the charges on or near QA and decay of the P+HA− state via the thermally activated P+BA− state.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2009a,

title = {Fluorescence hole-burning and site-selective studies of LHCII},

author = {Krzysztof Gibasiewicz and M Rutkowski and R van Grondelle},

url = {http://link.springer.com/10.1007/s11099-009-0037-0},

doi = {10.1007/s11099-009-0037-0},

issn = {0300-3604},

year  = {2009},

date = {2009-06-01},

journal = {Photosynthetica},

volume = {47},

number = {2},

pages = {232--240},

publisher = {Springer Netherlands},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Giera2009,

title = {Electron transfer from A−0 to A1 in Photosystem I from Chlamydomonas reinhardtii occurs in both the A and B branch with 25–30-ps lifetime},

author = {Wojciech Giera and Krzysztof Gibasiewicz and V M Ramesh and Su Lin and Andrew Webber},

url = {http://xlink.rsc.org/?DOI=b822938d},

doi = {10.1039/b822938d},

issn = {1463-9076},

year  = {2009},

date = {2009-06-01},

journal = {Physical Chemistry Chemical Physics},

volume = {11},

number = {25},

pages = {5186},

publisher = {The Royal Society of Chemistry},

abstract = {We have recorded transient absorption kinetics at 390 nm with picosecond resolution in order to observe electron transfer from the reduced primary acceptor, A−0, to the secondary acceptor, A1, in wild type and mutated Photosystem I from Chlamydomonas reinhardtii. In the mutants, the methionine axial ligand to the primary electron acceptor in either the A- or B-branch of electron transfer cofactors, was replaced with histidine. Both of the mutations reduced the formation of a positive signal at 390 nm, characteristic of A−1 to a level approximately half of that observed in wild type Photosystem I. It is concluded that in the mutated branch of Photosystem I, electron transfer from A−0 to A1 does not occur. The absorption kinetics resulting from subtraction of either of the mutants' traces from that of wild type is interpreted to reflect the kinetics of A- or B-side electron transfer from A−0 to A1 in the the wild type Photosystem I. Each of these traces could be fitted with a monoexpoenential decay characterized by the same amplitude and 25–30-ps lifetime. The almost identical effect of both mutations on A−1 formation confirm a similar engagement of both the A- ad B-branches in electron transfer to A1 in Photosystem I from C. reinhardtii. This observation is in contrast to the unidirectional electron transfer concluded from the studies on similar mutants of cyanobacterial Photosystem I.1 Thus, this contribution provides further evidence for functional differences between these two model Photosystems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2008,

title = {Primary Radical Pair P + H - Lifetime in Rhodobacter sphaeroides with Blocked Electron Transfer to Q A . Effect of o -Phenanthroline},

author = {Krzysztof Gibasiewicz and Maria Pajzderska},

url = {http://www.ncbi.nlm.nih.gov/pubmed/18215032 http://pubs.acs.org/doi/abs/10.1021/jp075184j},

doi = {10.1021/jp075184j},

issn = {1520-6106},

year  = {2008},

date = {2008-02-01},

journal = {The Journal of Physical Chemistry B},

volume = {112},

number = {6},

pages = {1858--1865},

abstract = {Transient absorption spectroscopy with a time resolution of approximately 1 ns was applied to study the decay of the primary radical pair P+H- in Rhodobacter sphaeroides R-26 reaction centers with blocked electron transfer from H- to QA. The block in the electron transfer was realized in two ways: by either reducing or removing QA. We found very different kinetics of the P+H- decay in these two cases. Convolution of the multiexponential decay with the instrument response function allowed resolution of as many as three kinetic components of textless1-, 3-4-, and 9-12-ns lifetimes in chromatophores with QA reduced and in isolated reaction centers both with QA either reduced or removed (with or without o-phenanthroline) but with variable relative amplitudes. Removing QA or adding o-phenanthroline to isolated reaction centers increased the amplitude of the slowest decay phase relative to that of the fastest phase. On the basis of these observations, we propose that reaction centers adopt three conformational states characterized by different decay kinetics of P+H-. These conformational states appear to be controlled by the charges in the vicinity of the QA site as revealed by the effects of QA reduction and o-phenanthroline-mediated protonation of the sites close to QA.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2007,

title = {Two equilibration pools of chlorophylls in the Photosystem I core antenna of Chlamydomonas reinhardtii},

author = {Krzysztof Gibasiewicz and V M Ramesh and Su Lin and Kevin Redding and Neal W Woodbury and Andrew N Webber},

url = {http://www.ncbi.nlm.nih.gov/pubmed/17611814 http://link.springer.com/10.1007/s11120-006-9125-1},

doi = {10.1007/s11120-006-9125-1},

issn = {0166-8595},

year  = {2007},

date = {2007-07-01},

journal = {Photosynthesis Research},

volume = {92},

number = {1},

pages = {55--63},

abstract = {Femtosecond transient absorption spectroscopy was applied for a comparative study of excitation decay in several different Photosystem I (PSI) core preparations from the green alga Chlamydomonas reinhardtii. For PSI cores with a fully interconnected network of chlorophylls, the excitation energy was equilibrated over a pool of chlorophylls absorbing at approximately 683 nm, independent of excitation wavelength [Gibasiewicz et al. J Phys Chem B 105:11498-11506, 2001; J Phys Chem B 106:6322-6330, 2002]. In preparations with impaired connectivity between chlorophylls, we have found that the spectrum of chlorophylls connected to the reaction center (i.e., with approximately 20 ps decay time) over which the excitation is equilibrated becomes excitation-wavelength-dependent. Excitation at 670 nm is finally equilibrated over chlorophylls absorbing at approximately 675 nm, whereas excitation at 695 nm or 700 nm is equilibrated over chlorophylls absorbing at approximately 683 nm. This indicates that in the vicinity of the reaction center there are two spectrally different and spatially separated pools of chlorophylls that are equally capable of effective excitation energy transfer to the reaction center. We propose that they are related to the two groups of central PSI core chlorophylls lying on the opposite sides of reaction center.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ramesh2007,

title = {Replacement of the methionine axial ligand to the primary electron acceptor A0 slows the A0− reoxidation dynamics in Photosystem I},

author = {V M Ramesh and Krzysztof Gibasiewicz and Su Lin and Scott E Bingham and Andrew N Webber},

url = {http://www.ncbi.nlm.nih.gov/pubmed/17316554 http://linkinghub.elsevier.com/retrieve/pii/S0005272806003896},

doi = {10.1016/j.bbabio.2006.12.013},

issn = {00052728},

year  = {2007},

date = {2007-02-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1767},

number = {2},

pages = {151--160},

abstract = {The recent crystal structure of photosystem I (PSI) from Thermosynechococcus elongatus shows two nearly symmetric branches of electron transfer cofactors including the primary electron donor, P(700), and a sequence of electron acceptors, A, A(0) and A(1), bound to the PsaA and PsaB heterodimer. The central magnesium atoms of each of the putative primary electron acceptor chlorophylls, A(0), are unusually coordinated by the sulfur atom of methionine 688 of PsaA and 668 of PsaB, respectively. We [Ramesh et al. (2004a) Biochemistry 43:1369-1375] have shown that the replacement of either methionine with histidine in the PSI of the unicellular green alga Chlamydomonas reinhardtii resulted in accumulation of A(0)(-) (in 300-ps time scale), suggesting that both the PsaA and PsaB branches are active. This is in contrast to cyanobacterial PSI where studies with methionine-to-leucine mutants show that electron transfer occurs predominantly along the PsaA branch. In this contribution we report that the change of methionine to either leucine or serine leads to a similar accumulation of A(0)(-) on both the PsaA and the PsaB branch of PSI from C. reinhardtii, as we reported earlier for histidine mutants. More importantly, we further demonstrate that for all the mutants under study, accumulation of A(0)(-) is transient, and that reoxidation of A(0)(-) occurs within 1-2 ns, two orders of magnitude slower than in wild type PSI, most likely via slow electron transfer to A(1). This illustrates an indispensable role of methionine as an axial ligand to the primary acceptor A(0) in optimizing the rate of charge stabilization in PSI. A simple energetic model for this reaction is proposed. Our findings support the model of equivalent electron transfer along both cofactor branches in Photosystem I.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2005a,

title = {Characterization of Low-Energy Chlorophylls in the PSI-LHCI Supercomplex from Chlamydomonas r einhardtii . A Site-Selective Fluorescence Study},

author = {Krzysztof Gibasiewicz and Anna Szrajner and Janne A Ihalainen and Marta Germano and Jan P Dekker and Rienk van Grondelle},

url = {http://www.ncbi.nlm.nih.gov/pubmed/16853744 http://pubs.acs.org/doi/abs/10.1021/jp0530909},

doi = {10.1021/jp0530909},

issn = {1520-6106},

year  = {2005},

date = {2005-11-01},

journal = {The Journal of Physical Chemistry B},

volume = {109},

number = {44},

pages = {21180--21186},

abstract = {Almost all photosystem I (PSI) complexes from oxygenic photosynthetic organisms contain chlorophylls that absorb at longer wavelength than that of the primary electron donor P700. We demonstrate here that the low-energy pool of chlorophylls in the PSI-LHCI complex from the green alga Chlamydomonas reinhardtii, containing five to six pigments, is significantly blue-shifted (A(max) at 700 nm at 4 K) compared to that in the PSI core preparations from several species of cyanobacteria and in PSI-LHCI particles from higher plants. This makes them almost isoenergetic with the primary donor. However, they keep the other characteristic features of "red" chlorophylls: clear spectral separation from the bulk chlorophylls, big Stokes shift revealing pronounced electron-phonon coupling, and large homogeneous and inhomogeneous broadening of approximately 170 and approximately 310 cm(-1), respectively.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2005b,

title = {Excitation Energy Transfer Pathways in Lhca4},

author = {Krzysztof Gibasiewicz and R Croce and T Morosinotto and J A Ihalainen and I H M van Stokkum and J P Dekker and R Bassi and R van Grondelle},

url = {http://www.ncbi.nlm.nih.gov/pubmed/15653744 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC1305248 http://linkinghub.elsevier.com/retrieve/pii/S0006349505732586},

doi = {10.1529/biophysj.104.049916},

issn = {00063495},

year  = {2005},

date = {2005-03-01},

journal = {Biophysical Journal},

volume = {88},

number = {3},

pages = {1959--1969},

publisher = {The Biophysical Society},

abstract = {EET in reconstituted Lhca4, a peripheral light-harvesting complex from Photosystem I of Arabidopsis thaliana, containing 10 chlorophylls and 2 carotenoids, was studied at room temperature by femtosecond transient absorption spectroscopy. Two spectral forms of Lut were observed in the sites L1 and L2, characterized by significantly different interactions with nearby chlorophyll a molecules. A favorable interpretation of these differences is that the efficiency of EET to Chls is about two times lower from the "blue" Lut in the site L1 than from the "red" Lut in the site L2 due to fast IC in the former case. A major part of the energy absorbed by the "red" Lut, approximately 60%-70%, is transferred to Chls on a sub-100-fs timescale from the state S(2) but, in addition, minor EET from the hot S(1) state within 400-500 fs is also observed. EET from the S(1) state to chlorophylls occurs also within 2-3 ps and is ascribed to Vio and/or "blue" Lut. EET from Chl b to Chl a is biphasic and characterized by time constants of approximately 300 fs and 3.0 ps. These rates are ascribed to EET from Chl b spectral forms absorbing at approximately 644 nm and approximately 650 nm, respectively. About 25% of the excited Chls a decays very fast-within approximately 15 ps. This decay is proposed to be related to the presence of the interacting Chls A5 and B5 located next to the carotenoid in the site L2 and may imply some photoprotective role for Lhca4 in the photosystem I super-complex.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ihalainen2005,

title = {Kinetics of excitation trapping in intact Photosystem I of Chlamydomonas reinhardtii and Arabidopsis thaliana},

author = {Janne A Ihalainen and Ivo H M van Stokkum and Krzysztof Gibasiewicz and Marta Germano and Rienk van Grondelle and Jan P Dekker},

url = {http://www.ncbi.nlm.nih.gov/pubmed/15694355 http://linkinghub.elsevier.com/retrieve/pii/S0005272804003299},

doi = {10.1016/j.bbabio.2004.11.007},

issn = {00052728},

year  = {2005},

date = {2005-02-01},

journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},

volume = {1706},

number = {3},

pages = {267--275},

abstract = {We measured picosecond time-resolved fluorescence of intact Photosystem I complexes from Chlamydomonas reinhardtii and Arabidopsis thaliana. The antenna system of C. reinhardtii contains about 30-60 chlorophylls more than that of A. thaliana, but lacks the so-called red chlorophylls, chlorophylls that absorb at longer wavelength than the primary electron donor. In C. reinhardtii, the main lifetimes of excitation trapping are about 27 and 68 ps. The overall lifetime of C. reinhardtii is considerably shorter than in A. thaliana. We conclude that the amount and energies of the red chlorophylls have a larger effect on excitation trapping time in Photosystem I than the antenna size.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ramesh2004,

title = {Bidirectional Electron Transfer in Photosystem I: Accumulation of A 0 - in A-Side or B-Side Mutants of the Axial Ligand to Chlorophyll A 0 †},

author = {V M Ramesh and Krzysztof Gibasiewicz and Su Lin and Scott E Bingham and Andrew N Webber},

url = {http://www.ncbi.nlm.nih.gov/pubmed/14756574 http://pubs.acs.org/doi/abs/10.1021/bi0354177},

doi = {10.1021/bi0354177},

issn = {0006-2960},

year  = {2004},

date = {2004-02-01},

journal = {Biochemistry},

volume = {43},

number = {5},

pages = {1369--1375},

abstract = {Photosystem I contains two potential electron transfer pathways between P(700) and F(X). These branches are made up of the electron transfer chain components A, A(0), and A(1). The primary electron acceptor A(0) is a chlorophyll a monomer that could be one or both of the two chlorophyll molecules, eC-A(3)/eC-B(3), identified in the 2.5 A resolution structure. The eC-A(3)/eC-B(3) chlorophylls are both coordinated by the sulfur atom of a methionine. This coordination is highly unusual, as interactions between the acid Mg(2+) and the soft base sulfur are weak. The eC-A(3)/eC-B(3) chlorophylls also are located close to one of the connecting chlorophylls that may link the antenna and the electron transfer chain chlorophylls. Due to their location in the structure, the eC-A(3)/eC-B(3) chlorophylls may play a role in both excitation energy transfer and electron transfer. To test the role of the eC-A(3)/eC-B(3) chlorophylls in electron transfer, Met-684 of PsaA and Met-664 of PsaB have been changed to His, Ser, and Leu. Replacement of either M(A684) or M(B664) results in a significant alteration in growth phenotype. The His and Leu mutants are very light sensitive in the presence of oxygen. Growth is impaired to a greater extent in the B-side mutants. However, all of the mutants are able to grow anaerobically at comparable rates. The His and Ser mutants all accumulate PSI at a level similar to that of wild type, whereas the Leu mutants have reduced amounts of PSI. Ultrafast transient absorbance measurements show that the (A(0)(-) - A(0)) difference signal accumulates in the MH(A684) and MH(B664) mutants under neutral conditions, demonstrating that electron transfer between A(0)(-) and A(1) is blocked or significantly slowed. The results show that both the A-branch and the B-branch of the ETC are active in PSI from Chlamydomonas reinhardtii.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2003,

title = {Excitonic Interactions in Wild-Type and Mutant PSI Reaction Centers},

author = {Krzysztof Gibasiewicz and V M Ramesh and Su Lin and Kevin Redding and Neal W Woodbury and Andrew N Webber},

url = {http://www.ncbi.nlm.nih.gov/pubmed/14507717 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC1303478 http://linkinghub.elsevier.com/retrieve/pii/S0006349503746773},

doi = {10.1016/S0006-3495(03)74677-3},

issn = {00063495},

year  = {2003},

date = {2003-10-01},

journal = {Biophysical Journal},

volume = {85},

number = {4},

pages = {2547--2559},

abstract = {Femtosecond excitation of the red edge of the chlorophyll a Q(Y) transition band in photosystem I (PSI), with light of wavelength textgreater or = 700 nm, leads to wide transient (subpicosecond) absorbance changes: positive DeltaA between 635 and 665 nm, and four negative DeltaA bands at 667, 675, 683, and 695 nm. Here we compare the transient absorbance changes after excitation at 700, 705, and 710 nm at 20 K in several PSI preparations of Chlamydomonas reinhardtii where amino acid ligands of the primary donor, primary acceptor, or connecting chlorophylls have been mutated. Most of these mutations influence the spectrum of the absorbance changes. This supports the view that the chlorophylls of the electron transfer chain as well as the connecting chlorophylls are engaged in the observed absorbance changes. The wide absorption spectrum of the electron transfer chain revealed by the transient measurements may contribute to the high efficiency of energy trapping in photosystem 1. Exciton calculations, based on the recent PSI structure, allow an assignment of the DeltaA bands to particular chlorophylls: the bands at 675 and 695 nm to the dimers of primary acceptor and accessory chlorophyll and the band at 683 nm to the connecting chlorophylls. The subpicosecond transient absorption bands decay may reflect rapid charge separation in the PSI reaction center.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2002,

title = {Excitation Dynamics in Eukaryotic PS I from Chlamydomonas r einhardtii CC 2696 at 10 K. Direct Detection of the Reaction Center Exciton States},

author = {Krzysztof Gibasiewicz and V M Ramesh and Su Lin and Neal W Woodbury and Andrew N Webber},

url = {http://pubs.acs.org/doi/abs/10.1021/jp014608l},

doi = {10.1021/jp014608l},

issn = {1520-6106},

year  = {2002},

date = {2002-06-01},

journal = {The Journal of Physical Chemistry B},

volume = {106},

number = {24},

pages = {6322--6330},

publisher = {American Chemical Society},

abstract = {Excitation energy transfer in PS I particles from the green alga Chlamydomonas reinhardtii CC 2696 was studied at 10 K by femtosecond transient absorption spectroscopy. Five-nm wide excitation pulses at 670, 680, 695, and 700 nm were applied to selectively excite different spectral forms contributing to the wide QY transition band of chlorophyll a. Absorbance changes between 630 and 770 nm, up to 100 ps after excitation, were collected with a time step of 54 fs during the first 5 ps. Excitation at 700 nm leads to a structured initial absorbance difference spectra with four positive bands clearly resolved at 634, 645, 652, and 661 nm, and four negative bands at 667, 675, 684, and 695 nm. These spectra are interpreted in terms of excitonic coupling between the six electron-transfer chlorophyll a molecules: a special pair, two accessory and two A0 chlorophylls. The negative bands were ascribed to photobleaching of the four one-exciton states in line with theoretical predictions (Beddard, G. S. J. Phys. Chem...},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2001a,

title = {Excitation Dynamics in the Core Antenna of PS I from Chlamydomonas r einhardtii CC 2696 at Room Temperature},

author = {Krzysztof Gibasiewicz and V M Ramesh and Alexander N Melkozernov and Su Lin and Neal W Woodbury and Robert E Blankenship and Andrew N Webber},

url = {http://pubs.acs.org/doi/abs/10.1021/jp012089g},

doi = {10.1021/jp012089g},

issn = {1520-6106},

year  = {2001},

date = {2001-11-01},

journal = {The Journal of Physical Chemistry B},

volume = {105},

number = {46},

pages = {11498--11506},

publisher = {American Chemical Society},

abstract = {Photosystem I particles from a eukaryotic organism, the green alga Chlamydomonas reinhardtii CC 2696, were studied by transient hole-burning spectroscopy at room temperature. Global analysis of the spectra recorded after excitation of chlorophyll a molecules in Photosystem I at selected wavelengths between 670 and 710 nm reveals excitation dynamics with subpicosecond, 2−3 ps, and 20−23 ps components. The subpicosecond and 2−3 ps components are ascribed to energy equilibration within the core antenna, whereas the 20−23 ps component is ascribed to energy trapping by the reaction center. Energy equilibration components describe both uphill and downhill energy transfer depending of the excitation wavelength. The initial transient absorbance bands after direct excitation of the red tail of the Qy transition band of chlorophyll a (at 700, 705, and 710 nm) are 25 nm wide and structured, revealing strongly coupled excited states among a group of molecules, most likely reaction center chlorophyll molecules. Excita...},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2001b,

title = {Modulation of Primary Radical Pair Kinetics and Energetics in Photosystem II by the Redox State of the Quinone Electron Acceptor QA},

author = {Krzysztof Gibasiewicz and Andrzej Dobek and Jacques Breton and Winfried Leibl},

url = {https://www.sciencedirect.com/science/article/pii/S0006349501761346 http://linkinghub.elsevier.com/retrieve/pii/S0006349501761346},

doi = {10.1016/S0006-3495(01)76134-6},

issn = {00063495},

year  = {2001},

date = {2001-04-01},

journal = {Biophysical Journal},

volume = {80},

number = {4},

pages = {1617--1630},

publisher = {Cell Press},

abstract = {Time-resolved photovoltage measurements on destacked photosystem II membranes from spinach with the primary quinone electron acceptor QA either singly or doubly reduced have been performed to monitor the time evolution of the primary radical pair P680+Pheo−. The maximum transient concentration of the primary radical pair is about five times larger and its decay is about seven times slower with doubly reduced compared with singly reduced QA. The possible biological significance of these differences is discussed. On the basis of a simple reversible reaction scheme, the measured apparent rate constants and relative amplitudes allow determination of sets of molecular rate constants and energetic parameters for primary reactions in the reaction centers with doubly reduced QA as well as with oxidized or singly reduced QA. The standard free energy difference $Delta$G° between the charge-separated state P680+Pheo− and the equilibrated excited state (ChlNP680)* was found to be similar when QA was oxidized or doubly reduced before the flash (∼−50 meV). In contrast, single reduction of QA led to a large change in $Delta$G° (∼+40 meV), demonstrating the importance of electrostatic interaction between the charge on QA and the primary radical pair, and providing direct evidence that the doubly reduced QA is an electrically neutral species, i.e., is doubly protonated. A comparison of the molecular rate constants shows that the rate of charge recombination is much more sensitive to the change in $Delta$G° than the rate of primary charge separation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz2001bb,

title = {Electron Transfer in the Reaction Center of the Photosynthetic Bacterium Rb. sphaeroides R-26 Measured by Transient Absorption in the Blue Spectral Range},

author = {Krzysztof Gibasiewicz and R Naskrecki and M Ziółek and M Lorenc and J Karolczak and J Kubicki and J Goc and J Miyake and Andrzej Dobek},

url = {http://link.springer.com/10.1023/A:1016695515341},

doi = {10.1023/A:1016695515341},

issn = {10530509},

year  = {2001},

date = {2001-01-01},

journal = {Journal of Fluorescence},

volume = {11},

number = {1},

pages = {33--40},

publisher = {Kluwer Academic Publishers-Plenum Publishers},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gibasiewicz1999,

title = {Re-examination of primary radical pair recombination in Rp. viridis with QA reduced},

author = {Krzysztof Gibasiewicz and K Brettel and Andrzej Dobek and W Leibl},

url = {https://www.sciencedirect.com/science/article/pii/S0009261499011586 http://linkinghub.elsevier.com/retrieve/pii/S0009261499011586},

doi = {10.1016/S0009-2614(99)01158-6},

issn = {00092614},

year  = {1999},

date = {1999-12-01},

journal = {Chemical Physics Letters},

volume = {315},

number = {1-2},

pages = {95--102},

publisher = {North-Holland},

abstract = {Charge recombination in the primary radical pair P+H− of the purple photosynthetic bacterium Rp. viridis with pre-reduced secondary acceptor QA, has been studied by time-resolved photovoltage measurements and transient absorption spectroscopy with a time resolution of 1 ns. The lifetime of P+H− was found to be 2.4–3 ns in intact membranes and ∼5 ns in isolated reaction centers, in contrast to a lifetime of ∼15 ns which has been widely accepted in the literature for reaction centers. The origin of the difference between lifetimes of P+H− in membranes and isolated reaction centers is discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}