title: Accumulation of non-protein metal-binding polypeptides (gamma-glutamyl-cysteinyl)n-glycine in selected cadmium-resistant tomato cells.
abstract: Tomato cell suspensions have been selected for sustained growth on normally lethal concentrations of CdCl2. In cadmium-resistant (CdR) cells, Cd2+ is found complexed with non-protein, cysteine-rich polypeptides which accumulate in high amounts when cells are grown in the presence of Cd2+. Sequence and linkage analysis of these peptides by triple quadrupole mass spectrometry establishes structures of (gamma-Glu-Cys)3-Gly and (gamma-Glu-Cys)4-Gly. Necessity of these peptides for the CdR phenotype is demonstrated by inhibition of their accumulation by buthionine sulfoximine, a specific inhibitor of gamma-glutamylcysteine synthetase. Treatment of CdR cells with a concentration of buthionine sulfoximine below that inhibiting growth in the absence of Cd2+ renders CdR cells sensitive to Cd2+ ion.
mesh_terms: D000595:Amino Acid Sequence; D019328:Buthionine Sulfoximine; D002104:Cadmium / Q000494:pharmacology*; D019256:Cadmium Chloride; D004351:Drug Resistance; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D013058:Mass Spectrometry; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D010641:Phenotype; D010944:Plants / Q000187:drug effects*
chemical_list: D002104:Cadmium; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; C042431:S-ethyl glutathione; D005978:Glutathione; D019256:Cadmium Chloride