title: Critical function of a Chlamydomonas reinhardtii putative polyphosphate polymerase subunit during nutrient deprivation.
abstract: Forward genetics was used to isolate Chlamydomonas reinhardtii mutants with altered abilities to acclimate to sulfur (S) deficiency. The ars76 mutant has a deletion that eliminates several genes, including VACUOLAR TRANSPORTER CHAPERONE1 (VTC1), which encodes a component of a polyphosphate polymerase complex. The ars76 mutant cannot accumulate arylsulfatase protein or mRNA and shows marked alterations in levels of many transcripts encoded by genes induced during S deprivation. The mutant also shows little acidocalcisome formation compared with wild-type, S-deprived cells and dies more rapidly than wild-type cells following exposure to S-, phosphorus-, or nitrogen (N)-deficient conditions. Furthermore, the mutant does not accumulate periplasmic L-amino acid oxidase during N deprivation. Introduction of the VTC1 gene specifically complements the ars76 phenotypes, suggesting that normal acidocalcisome formation in cells deprived of S requires VTC1. Our data also indicate that a deficiency in acidocalcisome function impacts trafficking of periplasmic proteins, which can then feed back on the transcription of the genes encoding these proteins. These results and the reported function of vacuoles in degradation processes suggest a major role of the acidocalcisome in reshaping the cell during acclimation to changing environmental conditions.
authors.affiliation: The Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305 maksoy1@stanford.edu.
authors.forename: Munevver
authors.initials: M
authors.lastname: Aksoy
authors.affiliation: The Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305 National Center for Genetic Engineering and Biotechnology, Pathum Thani 12120, Thailand.
authors.forename: Wirulda
authors.initials: W
authors.lastname: Pootakham
authors.affiliation: The Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305.
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Grossman
mesh_terms: D000595:Amino Acid Sequence; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D001192:Arylsulfatases / Q000235:genetics / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D015151:Immunoblotting; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation; D009584:Nitrogen / Q000172:deficiency / Q000378:metabolism; D010641:Phenotype; D010758:Phosphorus / Q000172:deficiency / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013455:Sulfur / Q000172:deficiency / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D027321:Anion Transport Proteins; D010940:Plant Proteins; D011122:Polyphosphates; D010758:Phosphorus; D013455:Sulfur; D001192:Arylsulfatases; D009584:Nitrogen