title: Chromate sensitivity in fission yeast is caused by increased glutathione reductase activity and peroxide overproduction.
abstract: The Cr(VI)-sensitive mutant chr-51S of the Schizosaccharomyces pombe accumulated chromate (CrO(4) (2-)) and reduced Cr(V) to much greater extent, than did its parental strain 6 chr(+). Sublethal doses of K(2)Cr(2)O(7) did not induce any adaptive stress response, while H(2)O(2) or menadione pretreatment proved protective against the cell injuries caused by Cr(VI). The intracellular GSH concentration in chr-51S cells was approximately half of that for the 6 chr(+). Moreover, the glutathione disulfide reducing capacity of chr-51S was characterized by significantly increased glutathione reductase (GR) and glucose-6-phosphate dehydrogenase activities. These data strongly suggested that, instead of GSH, the NADPH/GR system was the major one-electron Cr(VI) reductant in vivo. The increased Cr(V) reduction in chr-51S mutant was accompanied by high intracellular superoxide and peroxide concentrations, required for formation of the hydroxyl radical ((*)OH). The decreased intracellular GSH levels and the Cr(VI)-sensitive phenotype of the chr-51S cells indicates that GSH might act effectively against chromate by scavenging (*)OH.
authors.affiliation: Department of General and Environmental Microbiology, University of Pécs, Hungary. micro@ttk.pte.hu
authors.forename: Miklós
authors.initials: M
authors.lastname: Pesti
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Gazdag
authors.forename: Tamás
authors.initials: T
authors.lastname: Emri
authors.forename: Nelli
authors.initials: N
authors.lastname: Farkas
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Koósz
authors.forename: József
authors.initials: J
authors.lastname: Belágyi
authors.forename: István
authors.initials: I
authors.lastname: Pócsi
mesh_terms: D002857:Chromium / Q000032:analysis / Q000633:toxicity*; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis / Q000378:metabolism; D005978:Glutathione / Q000096:biosynthesis / Q000378:metabolism; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010084:Oxidation-Reduction; D010545:Peroxides / Q000032:analysis / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*
chemical_list: D010545:Peroxides; D002857:Chromium; D005954:Glucosephosphate Dehydrogenase; D005980:Glutathione Reductase; D005978:Glutathione