Expression of the Candida albicans morphogenesis regulator gene CZF1 and its regulation by Efg1p and Czf1p.

The ability of Candida albicans to transit between different cellular morphologies is believed to be important for virulence. Morphological transitions occur in response to a variety of environmental signals. One such signal is encountered when cells are grown in a semisolid matrix. An important regulator of cellular morphology is the putative transcription factor CZF1. Here we demonstrate that transcription of CZF1 is responsive to growth parameters such as the temperature, carbon source, growth phase of cells, and the physical environment. In wild-type cells, a CZF1 transcript of about 4 kb was expressed when cells were grown embedded in semisolid agar medium, as well as in late exponential phase when cells were grown in liquid medium. Deletion of EFG1, a key regulator of morphogenesis, abolished CZF1 expression. Overexpression of CZF1 revealed that this gene also autoregulates its expression. Efg1p and Czf1p were shown by chromatin immunoprecipitation to act by binding to the promoter of CZF1. The coupling of environmental cues to the expression of a morphogenetic transcription factor may allow C. albicans to coordinate morphogenesis in response to specific conditions encountered in the human host.