The expression of the pathogenic yeast Candida albicans catalase gene in response to hydrogen peroxide

The catalase gene of the pathogenic yeast Candida albicans was cloned and i ts expression was examined. Activity of the catalase was detected when cell s which were in the early logarithmic stage were treated with hydrogen pero xide. Additionally, activity was detected without any treatment to cells in the late logarithmic and stationary phases. When cells were cultured in ga lactose, glycerol, or ethanol, catalase activity was always observed withou t the hydrogen peroxide treatment, suggesting that glucose represses the in duction of catalase expression. To elucidate the molecular mechanism of cat alase expression, the putative gene for catalase and its 5' untranscribed r egion were cloned. Sequences of the gene and its potential regulatory regio n revealed several motifs, including a GC box-like element and stress-respo nsive element (STRE), which could be involved in the transcriptional regula tion. Northern analysis showed that hydrogen peroxide and sorbitol activate d transcription of the catalase. On the other hand, treatment of glucose st rictly repressed the expression of the catalase even when co-treated with h ydrogen peroxide. The expression of catalase against treatment with hydroge n peroxide took place very quickly and decreased slowly in the experimental condition adopted here. From these results, we assumed that the expression of the catalase in Candida albicans is regulated by various environmental conditions via motifs for transcriptional activation as in other yeast cata lases.