title: AtPCS1, a phytochelatin synthase from Arabidopsis: isolation and in vitro reconstitution.
abstract: Phytochelatins, a class of posttranslationally synthesized peptides, play a pivotal role in heavy metal, primarily Cd2+, tolerance in plants and fungi by chelating these substances and decreasing their free concentrations. Derived from glutathione and related thiols by the action of gamma-glutamylcysteine dipeptidyl transpeptidases (phytochelatin synthases; EC 2.3.2.15), phytochelatins consist of repeating units of gamma-glutamylcysteine followed by a C-terminal Gly, Ser, or beta-Ala residue [poly-(gamma-Glu-Cys)n-Xaa]. Here we report the suppression cloning of a cDNA (AtPCS1) from Arabidopsis thaliana encoding a 55-kDa soluble protein that enhances heavy-metal tolerance and elicits Cd2+-activated phytochelatin accumulation when expressed in Saccharomyces cerevisiae. On the basis of these properties and the sufficiency of immunoaffinity-purified epitope-tagged AtPCS1 polypeptide for high rates of Cd2+-activated phytochelatin synthesis from glutathione in vitro, AtPCS1 is concluded to encode the enzyme phytochelatin synthase.
authors.affiliation: Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: O K
authors.initials: OK
authors.lastname: Vatamaniuk
authors.forename: S
authors.initials: S
authors.lastname: Mari
authors.forename: Y P
authors.initials: YP
authors.lastname: Lu
authors.forename: P A
authors.initials: PA
authors.lastname: Rea
mesh_terms: D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment
chemical_list: D010940:Plant Proteins; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase