title: Phytochelatin synthase (PCS) protein is induced in Brassica juncea leaves after prolonged Cd exposure.
abstract: Higher plants respond to cadmium exposure with the production of phytochelatins (PCn), small heavy metal binding peptides, which are synthesized from glutathione by phytochelatin synthase (PCS). The isolation of a PCS cDNA clone from Brassica juncea L. cv. Vitasso, a candidate species for phytoremediation, is reported here. CLUSTAL analysis revealed a close relationship of BjPCS1 with PCS proteins from Arabidopsis thaliana and Thlaspi caerulescens. BjPCS1 expressed as recombinant protein in E. coli had PCS activity in vitro that was activated by 50 microM Cu and 200 microM Cd to a similar extent. Immunoblot analysis with an antiserum directed against recombinant BjPCS1 showed constitutive PCS expression during plant development. As a percentage of the total protein, the expression was higher in the roots, internodes and petioles in comparison with the leaf tissue. When B. juncea plants were treated with 25 microM cadmium, PCn accumulated increasingly over a 6 d period. Levels in shoots were about 3-fold higher than in roots. Prolonged cadmium exposure caused a significant increase of PCS protein in leaves, whereas in roots PCS protein levels were not affected.
authors.affiliation: Heidelberger Institut für Pflanzenwissenschaften, INF 360, D-69120 Heidelberg, Germany.
authors.forename: Senta
authors.initials: S
authors.lastname: Heiss
authors.forename: Andreas
authors.initials: A
authors.lastname: Wachter
authors.forename: Jochen
authors.initials: J
authors.lastname: Bogs
authors.forename: Christopher
authors.initials: C
authors.lastname: Cobbett
authors.forename: Thomas
authors.initials: T
authors.lastname: Rausch
mesh_terms: D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D005978:Glutathione; D008667:Metalloproteins / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009149:Mustard Plant / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D009928:Organ Specificity; D010802:Phylogeny; D054811:Phytochelatins; D018515:Plant Leaves / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D008667:Metalloproteins; D002104:Cadmium; D054811:Phytochelatins; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase; D005978:Glutathione