title: The role of the novel adenosine 5'-phosphosulfate reductase in regulation of sulfate assimilation of Physcomitrella patens.
abstract: Sulfate assimilation provides reduced sulfur for the synthesis of the amino acids cysteine and methionine and for a range of other metabolites. The key step in control of plant sulfate assimilation is the reduction of adenosine 5'-phosphosulfate to sulfite. The enzyme catalyzing this reaction, adenosine 5'phosphosulfate reductase (APR), is found as an iron sulfur protein in plants, algae, and many bacteria. In the moss Physcomitrella patens, however, a novel isoform of the enzyme, APR-B, has recently been discovered lacking the co-factor. To assess the function of the novel APR-B we used homologous recombination to disrupt the corresponding gene in P. patens. The knock-out plants were able to grow on sulfate as a sole sulfur source and the content of low molecular weight thiols was not different from wild type plants or plants where APR was disrupted. However, when treated with low concentrations of cadmium the APR-B knockout plants were more sensitive than both wild type and APR knockouts. In wild type P. patens, the two APR isoforms were not affected by treatments that strongly regulate this enzyme in flowering plants. The data thus suggest that in P. patens APS reduction is not the major control step of sulfate assimilation.
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany.
authors.forename: Gertrud
authors.initials: G
authors.lastname: Wiedemann
authors.forename: Anna
authors.initials: A
authors.lastname: Koprivova
authors.forename: Melanie
authors.initials: M
authors.lastname: Schneider
authors.forename: Cornelia
authors.initials: C
authors.lastname: Herschbach
authors.forename: Ralf
authors.initials: R
authors.lastname: Reski
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kopriva
mesh_terms: D019068:Bryopsida / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism*