title: Photosystem II does not possess a simple excitation energy funnel: time-resolved fluorescence spectroscopy meets theory.
abstract: The experimentally obtained time-resolved fluorescence spectra of photosystem II (PS II) core complexes, purified from a thermophilic cyanobacterium Thermosynechococcus vulcanus, at 5-180 K are compared with simulations. Dynamic localization effects of excitons are treated implicitly by introducing exciton domains of strongly coupled pigments. Exciton relaxations within a domain and exciton transfers between domains are treated on the basis of Redfield theory and generalized Förster theory, respectively. The excitonic couplings between the pigments are calculated by a quantum chemical/electrostatic method (Poisson-TrEsp). Starting with previously published values, a refined set of site energies of the pigments is obtained through optimization cycles of the fits of stationary optical spectra of PS II. Satisfactorily agreement between the experimental and simulated spectra is obtained for the absorption spectrum including its temperature dependence and the linear dichroism spectrum of PS II core complexes (PS II-CC). Furthermore, the refined site energies well reproduce the temperature dependence of the time-resolved fluorescence spectrum of PS II-CC, which is characterized by the emergence of a 695 nm fluorescence peak upon cooling down to 77 K and the decrease of its relative intensity upon further cooling below 77 K. The blue shift of the fluorescence band upon cooling below 77 K is explained by the existence of two red-shifted chlorophyll pools emitting at around 685 and 695 nm. The former pool is assigned to Chl45 or Chl43 in CP43 (Chl numbering according to the nomenclature of Loll et al. Nature2005, 438, 1040) while the latter is assigned to Chl29 in CP47. The 695 nm emitting chlorophyll is suggested to attract excitations from the peripheral light-harvesting complexes and might also be involved in photoprotection.
authors.affiliation: Division of Material Science (Physics), Graduate School of Science, Nagoya University, Nagoya, Japan. shibata@m.tohoku.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shibata
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Nishi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawakami
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
authors.forename: Thomas
authors.initials: T
authors.lastname: Renger
mesh_terms: D000458:Cyanobacteria / Q000201:enzymology*; D008958:Models, Molecular; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013997:Time Factors
chemical_list: D045332:Photosystem II Protein Complex
references.citation: Biophys J. 2006 Oct 15;91(8):2778-97
references.pmid: 16861264
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Mar;65(3 Pt 1):031919
references.pmid: 11909121
references.citation: Biochim Biophys Acta. 2006 Dec;1757(12):1657-68
references.pmid: 17070496
references.citation: J Phys Chem B. 2008 May 29;112(21):6695-702
references.pmid: 18461984
references.citation: Biochemistry. 2002 Dec 24;41(51):15224-33
references.pmid: 12484760
references.citation: Biochim Biophys Acta. 2011 Mar;1807(3):319-25
references.pmid: 21195048
references.citation: Photosynth Res. 2011 Oct;110(1):25-38
references.pmid: 21964859
references.citation: J Phys Chem B. 2008 Aug 14;112(32):9934-47
references.pmid: 18642950
references.citation: Biophys J. 2003 Jul;85(1):140-58
references.pmid: 12829471
references.citation: J Phys Chem B. 2010 Jul 15;114(27):9031-8
references.pmid: 20557037
references.citation: Photosynth Res. 2005 Jun;84(1-3):173-80
references.pmid: 16049771
references.citation: Proc Natl Acad Sci U S A. 1979 Sep;76(9):4170-4
references.pmid: 16592698
references.citation: J Am Chem Soc. 2010 Mar 17;132(10):3331-43
references.pmid: 20166713
references.citation: Biochemistry. 1995 Apr 11;34(14):4814-27
references.pmid: 7718588
references.citation: Phys Rev B Condens Matter. 1993 Sep 15;48(12):9066-9070
references.pmid: 10007127
references.citation: Biochemistry. 1991 Jul 30;30(30):7573-86
references.pmid: 1854756
references.citation: Photosynth Res. 2012 Mar;111(1-2):87-101
references.pmid: 21809112
references.citation: Nature. 2011 May 5;473(7345):55-60
references.pmid: 21499260
references.citation: J Biol Chem. 1994 May 13;269(19):13904-10
references.pmid: 8188669
references.citation: Nature. 2005 Dec 15;438(7070):1040-4
references.pmid: 16355230
references.citation: Nat Struct Mol Biol. 2009 Mar;16(3):334-42
references.pmid: 19219048
references.citation: Chemphyschem. 2010 Apr 26;11(6):1141-53
references.pmid: 20394099
references.citation: EMBO J. 2009 Oct 7;28(19):3052-63
references.pmid: 19696744
references.citation: J Phys Chem B. 2010 Mar 4;114(8):2954-63
references.pmid: 20141149
references.citation: J Phys Chem B. 2010 Sep 16;114(36):11884-98
references.pmid: 20722360
references.citation: Biophys J. 1998 Jul;75(1):521-7
references.pmid: 9649414
references.citation: Biophys J. 2005 Feb;88(2):986-98
references.pmid: 15556979
references.citation: Biochemistry. 1995 Apr 11;34(14):4798-813
references.pmid: 7718587
references.citation: Plant Cell Physiol. 2009 Sep;50(9):1674-80
references.pmid: 19667103
references.citation: Photosynth Res. 2011 Oct;110(1):39-48
references.pmid: 21986932
references.citation: Biochemistry. 2008 Mar 11;47(10):3143-54
references.pmid: 18278871
references.citation: Biochim Biophys Acta. 2006 Jul;1757(7):841-51
references.pmid: 16859635
references.citation: J Am Chem Soc. 2008 Apr 2;130(13):4431-46
references.pmid: 18327941
references.citation: Plant Cell Physiol. 2002 Oct;43(10):1112-6
references.pmid: 12407190
references.citation: Biophys J. 2008 Jul;95(1):105-19
references.pmid: 18339736
references.citation: J Am Chem Soc. 2010 Mar 31;132(12):4214-29
references.pmid: 20218564
references.citation: J Biol Chem. 2011 Apr 29;286(17):14812-9
references.pmid: 21339295
references.citation: Biochemistry. 2000 Dec 5;39(48):14739-44
references.pmid: 11101288
references.citation: Plant Physiol. 2007 Dec;145(4):1506-20
references.pmid: 17932304
references.citation: Front Biosci. 2004 May 01;9:1082-99
references.pmid: 14977531
references.citation: Phys Chem Chem Phys. 2013 Mar 14;15(10):3348-71
references.pmid: 23361062
references.citation: Photosynth Res. 2008 Feb-Mar;95(2-3):197-209
references.pmid: 17917787
references.citation: Biochemistry. 1993 Feb 23;32(7):1825-32
references.pmid: 8382523