AtPCS1, a phytochelatin synthase from Arabidopsis: isolation and in vitro reconstitution.
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.[1]References
- AtPCS1, a phytochelatin synthase from Arabidopsis: isolation and in vitro reconstitution. Vatamaniuk, O.K., Mari, S., Lu, Y.P., Rea, P.A. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
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