EFG1 is a major regulator of cell wall dynamics in Candida albicans as revealed by DNA microarrays

Cell wall dynamics in Candida albicans, the most common fungal pathogen in man, underlie regulatory processes during the yeast-to-hyphae transition. To analyse this regulation at the transcriptional level, we have established a DNA microarray representing genes implicated in cell wall biogenesis. Using these microarrays, we were able to identify YWP1 and HWP2 that are specifically transcribed in the yeast or hyphal growth form respectively. Cluster analysis revealed at least two major clusters of genes: cluster I comprised genes that were upregulated under at least one hyphae-inducing condition. Three as yet not further characterized genes were attributed to cluster II. These genes were transcribed in the yeast form of C. albicans and were downregulated in an EFG1-dependent manner under specific hyphae-inducing conditions. We show further that, in contrast to CPH1, EFG1 plays a major role in the transcriptional regulation of cell wall proteins under the conditions investigated. EFG1 was essential for the transcription of both hyphae-specific genes such as HWP1 and HWP2 as well as the yeast form-specific gene YWP1. Moreover, we found that, under various conditions, EFG1 also can act as a strong repressor for the transcription of RBE1, another not yet characterized cell wall protein. Overall, our data show that EFG1 plays a major role in the induction and repression of cell wall genes, not only in the hyphal form but also in the yeast form of C. albicans.