dr Wojciech Giera

@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{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{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{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{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{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}

}