The abc1 − /coq8 − respiratory-deficient mutant of Schizosaccharomyces pombe suffers from glutathione underproduction and hyperaccumulates Cd2+

Abstract

The abc1(-)/coq8(-) gene deletion respiratory-deficient mutant NBp17 of fission yeast Schizosaccharomyces pombe displayed a phenotypic fermentation pattern with enhanced production of glycerol and acetate, and also possessed oxidative stress-sensitive phenotypes to H(2)O(2), menadione, tBuOOH, Cd(2+), and chromate in comparison with its parental respiratory-competent strain HNT. As a consequence of internal stress-inducing mutation, adaptation processes to restore the redox homeostasis of mutant NBp17 cells were detected in minimal glucose medium. Mutant NBp17 produced significantly increased amounts of O(2)•- and H(2)O(2) as a result of the decreased internal glutathione concentration and the only slightly increased glutathione reductase activity. The Cr(VI) reduction capacity and hence the •OH production ability were decreased. The mutant cells demonstrated increased specific activities of superoxide dismutases and glutathione reductase (but not catalase) to detoxify at least partially the overproduction of reactive oxygen species. All these features may be explained by the decreased redox capacity of the mutant cells. Most notably, mutant NBp17 hyperaccumulated yellow CdS.

Overexpression of theYAP1,PDE2, andSTB3genes enhances the tolerance of yeast to oxidative stress induced by 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine

“…‡ Specific activities are given in unit (min mg protein) À1 . A single gene mutation-induced alteration in the redox state of yeast cells has already been reported (Gazdag et al, 2003(Gazdag et al, , 2011, but these are the first results indicating the consequences of overexpressed YAP1, PDE2, and STB3 genes in redox processes and their regulation. ¶ Specific activities are given in nmol (min mg protein) À1 .…”

“…We therefore analyzed the O À 2 , H 2 O 2 , and GSH concentrations and specific activities of antioxidant enzymes such the SODs (which catalyze the dismutation of O À 2 to H 2 O 2 ) localized in the cytoplasm (Cu/Zn-SOD) or the mitochondria (Mn-SOD), CAT (which inactivates H 2 O 2 to H 2 O), GPx (which catalyzes the oxidation of GSH to GSSG with the concomitant consumption of H 2 O 2 ), GR (which reduces GSSG to GSH at the expense of NADPH) in the parental strain BY4741 and its transformants bearing the YAP1, PDE2, and STB3 genes on a high-copy-number plasmid. In all experiments, mid-log-phase (18-h) cultures multiplied in minimal (YNB) medium were used to obtain cells in the same physiological status and to eliminate the possible antioxidant effects of the complete (YPD) medium (Gazdag et al, 2011). The results are presented in Fig.…”

“…(b) Growth in the presence of CTBT.cells in the same physiological status and to eliminate the possible antioxidant effects of the complete (YPD) medium(Gazdag et al, 2011). (a) Growth in the absence of CTBT.…”

Identification of Genes Required for Alternative Oxidase Production in the Neurospora crassa Gene Knockout Library

“…The kinase domain of Coq8 is thought to regulate the activity of Coq3, a ubiquinone biosynthetic enzyme (Tauche et al 2008). However, a coq8 deletion strain has also been shown to have a complex phenotype that includes underproduction of glutathione and sensitivity to oxidative stress (Gazdag et al 2011). Members of the same family of proteins have also been linked to oxidative stress in Arabidopsis thaliana (Jasinski et al 2008).…”

Diverse fission yeast genes required for responding to oxidative and metal stress: Comparative analysis of glutathione‐related and other defense gene deletions

“…; Gazdag et al . ). Glutathione‐ and phytochelatin‐deficient mutants were not sensitive to copper, but were highly sensitive to cadmium.…”