title: The 9-kDa phosphoprotein of photosystem II. Generation and characterisation of Chlamydomonas mutants lacking PSII-H and a site-directed mutant lacking the phosphorylation site.
abstract: The chloroplast gene psbH encodes a 9-10 kDa thylakoid membrane protein (PSII-H) that is associated with photosystem II and is subject to light-dependent phosphorylation at a threonine residue located on the stromal side of the membrane. The function of PSII-H is not known, neither is it clear what regulatory role phosphorylation may play in the control of PSII activity. Using particle gun-mediated transformation, we have created chloroplast transformants of Chlamydomonas reinhardtii in which the synthesis of PSII-H is prevented by the disruption of psbH, or in which the phosphorylatable threonine is replaced by alanine through site-directed mutagenesis of the gene. The mutants lacking PSII-H have a photosystem II-deficient phenotype, with no detectable functioning PSII complex present in whole cells or isolated thylakoid membranes. In contrast, the alanine mutant (T3A) grows photoautotrophically, and PSII activity is comparable to wild-type cells as determined by various biochemical and biophysical assays.
authors.affiliation: UCL Photosynthesis Group, Department of Biology, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: H E
authors.initials: HE
authors.lastname: O'Connor
authors.forename: S V
authors.initials: SV
authors.lastname: Ruffle
authors.forename: A J
authors.initials: AJ
authors.lastname: Cain
authors.forename: Z
authors.initials: Z
authors.lastname: Deak
authors.forename: I
authors.initials: I
authors.lastname: Vass
authors.forename: J H
authors.initials: JH
authors.lastname: Nugent
authors.forename: S
authors.initials: S
authors.lastname: Purton
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D017931:DNA Primers; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008027:Light; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015183:Restriction Mapping; D013912:Threonine
chemical_list: D017931:DNA Primers; D010750:Phosphoproteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011994:Recombinant Proteins; C063224:photosystem II, psbH subunit; D013912:Threonine