title: Molecular cloning and characterization of a phytochelatin synthase gene, PvPCS1, from Pteris vittata L.
abstract: Pteris vittata L. is a staggeringly efficient arsenic hyperaccumulator that has been shown to be capable of accumulating up to 23,000 microg arsenic g(-1), and thus represents a species that may fully exploit the adaptive potential of plants to toxic metals. However, the molecular mechanisms of adaptation to toxic metal tolerance and hyperaccumulation remain unknown, and P. vittata genes related to metal detoxification have not yet been identified. Here, we report the isolation of a full-length cDNA sequence encoding a phytochelatin synthase (PCS) from P. vittata. The cDNA, designated PvPCS1, predicts a protein of 512 amino acids with a molecular weight of 56.9 kDa. Homology analysis of the PvPCS1 nucleotide sequence revealed that it has low identity with most known plant PCS genes except AyPCS1, and the homology is largely confined to two highly conserved regions near the 5'-end, where the similarity is as high as 85-95%. The amino acid sequence of PvPCS1 contains two Cys-Cys motifs and 12 single Cys, only 4 of which (Cys-56, Cys-90/91, and Cys-109) in the N-terminal half of the protein are conserved in other known PCS polypeptides. When expressed in Saccharomyces cerevisae, PvPCS1 mediated increased Cd tolerance. Cloning of the PCS gene from an arsenic hyperaccumulator may provide information that will help further our understanding of the genetic basis underlying toxic metal tolerance and hyperaccumulation.
authors.affiliation: Centro di Ricerca Interdipartimentale per le Biotechnologie Innovative, Universita' di Padova, Via G. Colombo 3, 35121 Padua, Italy. ruibindong@hotmail.com
authors.forename: Ruibin
authors.initials: R
authors.lastname: Dong
authors.forename: Elide
authors.initials: E
authors.lastname: Formentin
authors.forename: Carmen
authors.initials: C
authors.lastname: Losseso
authors.forename: Francesco
authors.initials: F
authors.lastname: Carimi
authors.forename: Piero
authors.initials: P
authors.lastname: Benedetti
authors.forename: Mario
authors.initials: M
authors.lastname: Terzi
authors.forename: Fiorella Lo
authors.initials: FL
authors.lastname: Schiavo
mesh_terms: D019881:Aminoacyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001149:Arsenates / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D002104:Cadmium / Q000494:pharmacology; D003001:Cloning, Molecular; D018076:DNA, Complementary; D025141:Drug Resistance, Fungal; D005978:Glutathione / Q000378:metabolism; D008969:Molecular Sequence Data; D054811:Phytochelatins; D032495:Pteris / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D001149:Arsenates; D018076:DNA, Complementary; D002104:Cadmium; D054811:Phytochelatins; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase; D005978:Glutathione