title: A single residue controls electron transfer gating in photosynthetic reaction centers.
abstract: Interquinone QA-→ QBelectron-transfer (ET) in isolated photosystem II reaction centers (PSII-RC) is protein-gated. The temperature-dependent gating frequency "k" is described by the Eyring equation till levelling off at T ≥ 240 °K. Although central to photosynthesis, the gating mechanism has not been resolved and due to experimental limitations, could not be explored in vivo. Here we mimic the temperature dependency of "k" by enlarging VD1-208, the volume of a single residue at the crossing point of the D1 and D2 PSII-RC subunits in Synechocystis 6803 whole cells. By controlling the interactions of the D1/D2 subunits, VD1-208(or 1/T) determines the frequency of attaining an ET-active conformation. Decelerated ET, impaired photosynthesis, D1 repair rate and overall cell physiology upon increasing VD1-208to above 130 Å3, rationalize the >99% conservation of small residues at D1-208 and its homologous motif in non-oxygenic bacteria. The experimental means and resolved mechanism are relevant for numerous transmembrane protein-gated reactions.
authors.affiliation: The Weizmann Institute of Science, Department of Plant and Environmental Sciences, 76100 Rehovot, Israel.
authors.forename: Oksana
authors.initials: O
authors.lastname: Shlyk
authors.affiliation: The Weizmann Institute of Science, Department of Plant and Environmental Sciences, 76100 Rehovot, Israel.
authors.forename: Ilan
authors.initials: I
authors.lastname: Samish
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Science, 37005 České Budějovice, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Matěnová
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Science, 37005 České Budějovice, Czech Republic.
authors.forename: Alexander
authors.initials: A
authors.lastname: Dulebo
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Science, 37005 České Budějovice, Czech Republic.
authors.forename: Helena
authors.initials: H
authors.lastname: Poláková
authors.affiliation: University of South Bohemia in České Budějovice, Faculty of Science, 37005 České Budějovice, Czech Republic.|Institute of Microbiology CAS, Department of Phototrophic Microorganisms, 37981 Trebon, Czech Republic.
authors.forename: David
authors.initials: D
authors.lastname: Kaftan
authors.affiliation: The Weizmann Institute of Science, Department of Plant and Environmental Sciences, 76100 Rehovot, Israel.
authors.forename: Avigdor
authors.initials: A
authors.lastname: Scherz
mesh_terms: D019069:Cell Respiration / Q000235:genetics; D004579:Electron Transport / Q000235:genetics; D004583:Electrons; D007700:Kinetics; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000235:genetics; D010788:Photosynthesis / Q000235:genetics*; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics; D046939:Synechocystis / Q000737:chemistry* / Q000235:genetics
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex