Repression of CDC28 reduces the expression of the morphology-related transcription factors, Efg1p, Nrg1p, Rbf1p, Rim101p, Fkh2p and Tec1p and induces cell elongation in Candida albicans.

The ability of the human fungal pathogen Candida albicans to transit its cell shape is important for its pathogenicity. To obtain additional evidence that the cell cycle of C. albicans is associated with its morphology, we generated and characterized a conditional mutant of C. albicans CDC28, a cyclin-dependent kinase. In the constructed strain, the expression of CDC28 was regulated by the MET3 promoter and could be repressed in the presence of methionine and cysteine. Cdc28p-depleted cells demonstrated highly polarized growth and wider filaments than serum-induced hyphae. Hyphae-specific genes, HWP1, RBT4 and ECE1, were activated in the elongated filaments caused by the Cdc28p depletion. Furthermore, the protein expression levels of the transcription factors involved in morphological transition, Efg1p, Nrg1p, Rbf1p, Rim101p, Fkh2p and Tec1p, decreased under conditions that repress CDC28 expression. Taken together, these data indicate that repression of CDC28 affected the protein levels of the morphology-related transcription factors, the regulation of hyphae-specific genes and cell shape in C. albicans.