MOLECULAR-CLONING OF A RHO-FAMILY, CDC42CA GENE FROM CANDIDA-ALBICANSAND ITS MESSENGER-RNA EXPRESSION CHANGES DURING MORPHOGENESIS

The small GTP-binding protein family regulates various cell functions in mammalian and yeast cells. In the yeast Saccharomyces cerevisiae it has been known to be involved in vegetative growth. As an initial att empt to explore the involvement of CDC42, a member of this family, in the regulation of morphological changes in Candida albicans, we isolat ed a gene encoding this protein (CDC42Ca) from this fungus. The sequen ce of isolated gene revealed an open reading frame of 570 nucleotides with the potential to encode a protein of 190 amino acids with a predi cted molecular weight of 20.5 kDa. The deduced amino acid sequence was highly homologous to CDC42s from yeast (87.8%), human (76.4%) and Cae norhabditis elegans (73.7%). The CDC42Ca mRNA level showed a transient increase with a peak at 2 h after the fresh medium shift (28 degrees C) when cells synchronously formed buds, whereas it displayed a gradua l increase up to 12 h after the medium shift (37 degrees C) with elong ation of germ tubes. This suggests that CDC42 may play a role in the b ud emergence and also germ tube formation in C. albicans.