Edited by Miguel De la RosaKeywords: Methylglyoxal Glutathione Alcohol dehydrogenase 1 G2-phase arrest Candida albicans a b s t r a c tWe purified a fraction that showed NAD + -linked methylglyoxal dehydrogenase activity, directly catalyzing methylglyoxal oxidation to pyruvate, which was significantly increased in glutathionedepleted Candida albicans. It also showed NADH-linked methylglyoxal-reducing activity. The fraction was identified as a NAD + -linked alcohol dehydrogenase (ADH1) through mass spectrometric analyses. In ADH1-disruptants of both the wild type and glutathione-depleted cells, the intracellular methylglyoxal concentration increased significantly; defects in growth, differentiation, and virulence were observed; and G2-phase arrest was induced.

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Edited by Dietmar J. Manstein Keywords:Transcriptional repressor Ssn6 Rpd31 Filamentous growth Candida albicans a b s t r a c t Ssn6 is a crucial regulator of morphological transition and virulence in the fungal pathogen Candida albicans. Ssn6 has previously been reported to act in complex with the transcriptional repressor Tup1. Here, we report that Ssn6 also interacts with the histone deacetylase Rpd31, independently of Tup1. The ssn6/rpd31 double mutant strain formed elongated filaments, but failed to form filament extension, and this coincided with the down-regulation of the filament extension gene UME6. Occupancy patterns of Ssn6 and Rpd31 differed at the promoters of UME6 and the metabolic gene INO1. These findings indicate that, in C. albicans, Ssn6 has dual roles in filament development, depending on the interaction with Rpd31.

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Edited by Miguel De la RosaKeywords: Erythroascorbate peroxidase D-Erythroascorbic acid Methylglyoxal Reactive oxygen species Candida albicans a b s t r a c t Candida albicans D-erythroascorbate peroxidase (EAPX1), which can catalyze the oxidation of D-erythroascorbic acid (EASC) to water, was observed to be inducible in EAPX1-deficient and EAPX1-overexpressing cells via activity staining. EAPX1-deficient cells have remarkably increased intracellular reactive oxygen species and methylglyoxal independent of the intracellular EASC content. The increased methylglyoxal caused EAPX1-deficient cells to activate catalase-peroxidase and cytochrome c peroxidase, which led to defects in cell growth, viability, mitochondrial respiration, filamentation and virulence. These findings indicate that EAPX1 mediates cell differentiation and virulence by regulating intracellular methylglyoxal along with oxidative stresses, regardless of endogenous EASC biosynthesis or alternative oxidase expression.