title: The PsbY protein is not essential for oxygenic photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803.
abstract: A tetra-manganese cluster in the photosystem II (PSII) pigment-protein complex plays a critical role in the photosynthetic oxygen evolution process. PsbY, a small membrane-spanning polypeptide, has recently been suggested to provide a ligand for manganese in PSII (A.E. Gau, H.H. Thole, A. Sokolenko, L. Altschmied, R.G. Herrmann, E.K. Pistorius [1998] Mol Gen Genet 260: 56-68). We have constructed a mutant strain of the cyanobacterium Synechocystis sp. PCC 6803 with an inactivated psbY gene (sml0007). Southern-blot and polymerase chain reaction analysis showed that the mutant had completely segregated. However, the DeltapsbY mutant cells grew normally under photoautotrophic conditions. Moreover, growth of the wild-type and mutant cells were similar under high-light photoinhibition conditions, as well as in media without any added manganese, calcium, or chloride, three required inorganic cofactors for the oxygen-evolving complex of PSII. Analysis of steady-state and flash-induced oxygen evolution, fluorescence induction, and decay kinetics, and thermoluminescence profiles demonstrated that the DeltapsbY mutant cells have normal photosynthetic activities. We conclude that the PsbY protein in Synechocystis 6803 is not essential for oxygenic photosynthesis and does not provide an important binding site for manganese in the oxygen-evolving complex of PSII.
authors.affiliation: Department of Biology, Box 1137, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: M
authors.initials: M
authors.lastname: Meetam
authors.forename: N
authors.initials: N
authors.lastname: Keren
authors.forename: I
authors.initials: I
authors.lastname: Ohad
authors.forename: H B
authors.initials: HB
authors.lastname: Pakrasi
mesh_terms: D001426:Bacterial Proteins; D002734:Chlorophyll / Q000378:metabolism; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008163:Luminescent Measurements; D008565:Membrane Proteins; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D015183:Restriction Mapping; D014169:Transformation, Bacterial; D014512:Ureohydrolases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C492036:Psby protein, Synechocystis; D002734:Chlorophyll; D014512:Ureohydrolases; D010100:Oxygen