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- Title
Tolerance to toxic metals by a gene family of phytochelatin synthases from plants and yeast.
- Authors
Stephan. Clemens; Kim, Eugene J.; Neumann, Dieter; Schroeder, Julian I.
- Abstract
Phytochelatins play major roles in metal detoxification in plants and fungi. However, genes encoding phyto-chelatin synthases have not yet been identified. By screening for plant genes mediating metal tolerance we identified a wheat cDNA, TaPCS1, whose expression in Saccharomyces cerevisiae results in a dramatic increase in cadmium tolerance. TaPCS1 encodes a protein of ∼55 kDa with no similarity to proteins of known function. We identified homologs of this new gene family from Arabidopsis thaliana, Schizosaccharo-myces pombe, and interestingly also Caenorhabditis elegans. The Arabidopsis and S.pombe genes were also demonstrated to confer substantial increases in metal tolerance in yeast. PCS-expressing cells accumulate more Cd2+ than controls. PCS expression mediates Cd2+ tolerance even in yeast mutants that are either deficient in vacuolar acidification or impaired in vacu-olar biogenesis. PCS-induced metal resistance is lost upon exposure to an inhibitor of glutathione biosynthesis, a process necessary for phytochelatin formation. Schizosaccharomyces pombe cells disrupted in the PCS gene exhibit hypersensitivity to Cd2+ and Cu2+ and are unable to synthesize phytochelatins upon Cd2+ exposure as determined by HPLC analysis. Saccharo-myces cerevisiae cells expressing PCS produce phyto-chelatins. Moreover, the recombinant purified S.pombe PCS protein displays phytochelatin synthase activity. These data demonstrate that PCS genes encode phyto-chelatin synthases and mediate metal detoxification in eukaryotes.
- Publication
EMBO Journal, 1999, Vol 18, Issue 12, p3325
- ISSN
0261-4189
- Publication type
Academic Journal
- DOI
10.1093/emboj/18.12.3325