Roles of vacuolar H⁺-ATPase in the oxidative stress response ofCandida glabrata

Abstract

Vacuolar H(+)-ATPase (V-ATPase) is responsible for the acidification of eukaryotic intracellular compartments and plays an important role in oxidative stress response (OSR), but its molecular bases are largely unknown. Here, we investigated how V-ATPase is involved in the OSR by using a strain lacking VPH2, which encodes an assembly factor of V-ATPase, in the pathogenic fungus Candida glabrata The loss of Vph2 resulted in increased H2O2 sensitivity and intracellular reactive oxygen species (ROS) level independently of mitochondrial functions. The Δvph2 mutant also displayed growth defects under alkaline conditions accompanied by the accumulation of intracellular ROS and these phenotypes were recovered in the presence of the ROS scavenger N-acetyl-l-cysteine. Both expression and activity levels of mitochondrial manganese superoxide dismutase (Sod2) and catalase (Cta1) were decreased in the Δvph2 mutant. Phenotypic analyses of strains lacking and overexpressing these genes revealed that Sod2 and Cta1 play a predominant role in endogenous and exogenous OSR, respectively. Furthermore, supplementation of copper and iron restored the expression of SOD2 specifically in the Δvph2 mutant, suggesting that the homeostasis of intracellular cupper and iron levels maintained by V-ATPase was important for the Sod2-mediated OSR. This report demonstrates novel roles of V-ATPase in the OSR in C. glabrata.

Identification of Essential Genes and Fluconazole Susceptibility Genes inCandida glabrataby ProfilingHermesTransposon Insertions

“…Twelve of these mutants encode critical subunits of the V-ATPase or its assembly factors (Fig. 3C, red circles), and one gene (VPH2) has been confirmed as non-essential in C. glabrata by knockout mutation (Nishikawa et al 2016).…”

Genome-Wide Identification of Genes Involved in General Acid Stress and Fluoride Toxicity in Saccharomyces cerevisiae

“…This result suggests that V-ATPase might function beyond intracellular pH maintenance in resisting acid toxicity. Several reports have linked vacuolar function with oxidative stress resistance, although the mechanism is still unknown (Milgrom et al, 2007;Diab and Kane, 2013;Charoenbhakdi et al, 2016;Nishikawa et al, 2016). Deletion of V-ATPase subunits in yeast results in hypersensitivity to a wide variety of oxidative stresses.…”

Engineering β-oxidation in Yarrowia lipolytica for methyl ketone production

“…4). Vacuoles play an important role in the cellular oxidative stress response (Nishikawa et al, 2016). Therefore, the presence of larger vacuoles may be a consequence of enhanced ROS detoxification activity.…”