The Cr(VI)-sensitive mutant chr-51S of the Schizosaccharomyces pombe accumulated chromate (CrO42-) and reduced Cr(V) to much greater extent, than did its parental strain 6 chr+. Sublethal doses of K2Cr2O7 did not induce any adaptive stress response, while H2O2 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.
|Number of pages||12|
|Journal||Journal of basic microbiology|
|Publication status||Published - Dec 1 2002|
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology