title: The D1-173 amino acid is a structural determinant of the critical interaction between D1-Tyr161 (TyrZ) and D1-His190 in Photosystem II.
abstract: The main cofactors of Photosystem II (PSII) are borne by the D1 and D2 subunits. In the thermophilic cyanobacterium Thermosynechococcus elongatus, three psbA genes encoding D1 are found in the genome. Among the 344 residues constituting the mature form of D1, there are 21 substitutions between PsbA1 and PsbA3, 31 between PsbA1 and PsbA2, and 27 between PsbA2 and PsbA3. In a previous study (Sugiura et al., J. Biol. Chem. 287 (2012), 13336-13347) we found that the oxidation kinetics and spectroscopic properties of TyrZ were altered in PsbA2-PSII when compared to PsbA(1/3)-PSII. The comparison of the different amino acid sequences identified the residues Cys144 and Pro173 found in PsbA1 and PsbA3, as being substituted in PsbA2 by Pro144 and Met173, and thus possible candidates accounting for the changes in the geometry and/or the environment of the TyrZ/His190 phenol/imidizol motif. Indeed, these amino acids are located upstream of the α-helix bearing TyrZ and between the two α-helices bearing TyrZ and its hydrogen-bonded partner, D1/His190. Here, site-directed mutants of PSII, PsbA3/Pro173Met and PsbA2/Met173Pro, were analyzed using X- and W-band EPR and UV-visible time-resolved absorption spectroscopy. The Pro173Met substitution in PsbA2-PSII versus PsbA3-PSII is shown to be the main structural determinant of the previously described functional differences between PsbA2-PSII and PsbA3-PSII. In PsbA2-PSII and PsbA3/Pro173Met-PSII, we found that the oxidation of TyrZ by P680+● was specifically slowed during the transition between S-states associated with proton release. We thus propose that the increase of the electrostatic charge of the Mn4CaO5 cluster in the S2 and S3 states could weaken the strength of the H-bond interaction between TyrZ● and D1/His190 in PsbA2 versus PsbA3 and/or induce structural modification(s) of the water molecules network around TyrZ.
authors.affiliation: Proteo-Science Research Center, Ehime University, Bunkyo-cho, Matsuyama Ehime, 790-8577, Japan; Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan; PRESTO, Science and Technology Agency (JST), 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan. Electronic address: miwa.sugiura@ehime-u.ac.jp.
authors.forename: Miwa
authors.initials: M
authors.lastname: Sugiura
authors.affiliation: Proteo-Science Research Center, Ehime University, Bunkyo-cho, Matsuyama Ehime, 790-8577, Japan.
authors.forename: Yui
authors.initials: Y
authors.lastname: Ozaki
authors.affiliation: Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Cox
authors.affiliation: Institut de Biologie Physico-Chimique, UMR 7141 CNRS and Université Pierre et Marie Curie, 13 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rappaport
authors.affiliation: iBiTec-S, CNRS UMR 8221, CEA Saclay, 91191 Gif-sur-Yvette, France. Electronic address: alain.boussac@cea.fr.
authors.forename: Alain
authors.initials: A
authors.lastname: Boussac
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000596:Amino Acids / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D000458:Cyanobacteria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006639:Histidine / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013053:Spectrophotometry; D014443:Tyrosine / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D021122:Protein Subunits; C422369:photosystem II, psbA subunit; D014443:Tyrosine; D006639:Histidine; D010100:Oxygen