title: Yz. reduction kinetics in the absence of the manganese-stabilizing protein of photosystem II.
abstract: Decay of Signal IIvf of photosystem II (PSII), under repetitive flash conditions, was examined in whole cells of wild-type Synechocystis sp. PCC6803 and in cells of an engineered strain, delta psbO, which lacks the extrinsic 33 kDa manganese-stabilizing protein (MSP). Previous polarographic analysis had shown that O2 release during the S3-->[S4]-->S0 transition of the catalytic cycle is significantly retarded in the delta psbO strain relative to the wild-type [Burnap et al. (1992) Biochemistry 31, 7404-7410]. The present experiments provide evidence that a parallel retardation in the rate of reduction of photooxidized Yz by the H2O oxidation complex is due to the absence of MSP. The half-time of the Signal IIvf component, corresponding to Yz. reduction during the S3-->[S4]-->S0 transition, was estimated to be 1.2 and 6.0 ms in the wild-type and delta psbO cells, respectively.
authors.affiliation: Department of Chemistry, Faculty of Science, Australian National University, Canberra, Australia.
authors.forename: M R
authors.initials: MR
authors.lastname: Razeghifard
authors.forename: T
authors.initials: T
authors.lastname: Wydrzynski
authors.forename: R J
authors.initials: RJ
authors.lastname: Pace
authors.forename: R L
authors.initials: RL
authors.lastname: Burnap
mesh_terms: D002384:Catalysis; D000458:Cyanobacteria / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008345:Manganese / Q000378:metabolism; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D011506:Proteins; C054266:photosystem II manganese-stabilizing protein; D008345:Manganese