title: Role of SulP, a nuclear-encoded chloroplast sulfate permease, in sulfate transport and H2 evolution in Chlamydomonas reinhardtii.
abstract: Antisense technology was applied to the green alga Chlamydomonas reinhardtiito probe the function of a novel nuclear gene encoding a chloroplast-envelope localized sulfate permease (SulP; GenBank Accession Numbers AF467891 and AF481828). Analysis showed that antiSulP transformants are impaired in sulfate uptake, a consequence of repression in the SulP gene expression. Antisense antiSulP transformants exhibited a sulfur-deprivation phenotype, strong induction of arylsulfatase activity, and global induction of sulfate assimilation gene expression. In sealed cultures, opposite to the wild-type control, antiSulP strains photo-evolved H2, underlining the notion of sulfate uptake limitation by the chloroplast, a slow-down in the rate of oxygen evolution, establishment of anaerobiosis due to internal respiration and spontaneous expression of the [Fe]-hydrogenase in these strains. It is concluded that antiSulP strains are promising as tools to limit the supply of sulfates to the chloroplast, leading to a down-regulation of H2O-oxidation and O2-evolution activity, to the constitutive expression of the [Fe]-hydrogenase and continuous H2-photoproduction in Chlamydomonas reinhardtii.Thus, antisulPstrains might permit a study of the biochemistry of H2 metabolism in this green alga under constitutive anaerobic oxygenic photosynthesis conditions.
authors.affiliation: Department of Plant & Microbial Biology, University of California, Berkeley, CA 94720-3102, USA.
authors.forename: Hsu-Ching
authors.initials: HC
authors.lastname: Chen
authors.forename: A Jamila
authors.initials: AJ
authors.lastname: Newton
authors.forename: Anastasios
authors.initials: A
authors.lastname: Melis
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000378:metabolism*; D001693:Biological Transport, Active; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology*; D018506:Gene Expression Regulation, Plant; D006859:Hydrogen / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism*; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D027321:Anion Transport Proteins; D010940:Plant Proteins; D013431:Sulfates; D006859:Hydrogen; C022702:sulfate permease