The cellular resistance against oxidative stress (HO ) is independent of neutral trehalase (Ntc1p) activity in Candida albicans

The protective role of trehalose against oxidative stress caused by hydrogen peroxide in Candida albicans has been investigated in the homozygous mutant ntc1Δ/ntc1Δ, disrupted in the NTC1 gene, which encodes the neutral (cytosolic) trehalase (Ntc1p). After a severe oxidative exposure (50 mM HO), both parental (CAI-4) and ntc1Δ/ntc1Δ exponential-phase cells stored large amounts of intracellular trehalose. In turn, the degree of cell survival was roughly equivalent in both strains, although slightly higher in ntc1Δ/ntc1Δ cultures. The mechanism of 'adaptive tolerance' was functional in the two strains. Thus, a gently oxidative pretreatment (5 mM HO) increased the recovery of cellular viability when it was followed by a severe challenge (50 mM H O); this phenomenon was accompanied by a significant elevation of the endogenous trehalose content. Oxidative stress also induced specific activation of the antioxidant enzymes catalase and glutathione reductase upon gentle oxidative treatment (5 mM HO), whereas superoxide dismutase activity was only activated upon prolonged exposure. Taken together, these results strongly suggest that in C. albicans neutral trehalase activity does not play an essential role in the protective response against oxidative stress. They also suggest that a diminished Ntc1p activity might favour the growth of C. albicans cells subjected to a strong oxidative exposure. © 2005 Federation of European Microbiological Societies Published by Blackwell Publishing Ltd. All rights reserved.