Evaluation of the CaMAL2 promoter for regulated expression of genes in Candida albicans

An expression vector (CIp10-MAL2p) for use in Candida albicans has been con structed in which a gene of interest can be placed under the control of the CaMAL2 maltase promoter and stably integrated at the CaRP10 locus. Using t his vector to express the Candida URA3 gene from the CaMAL2 promoter, we ha ve demonstrated tight regulation of CaUXA3 expression by carbon source. Thu s under conditions when the CaMAL2 promoter is not induced, expression of C andida URA3 was unable either to complement a C. albicans ura3 mutation or to confer sensitivity to 5-fluoroorotic acid, a compound which is highly to xic to URA3 strains. Since Candida albicans is an obligate diploid organism , analysis of gene function requires manipulation of both copies of any gen e of interest. Our expression vector provides a strategy by which the remai ning copy of a gene of interest can be placed under CaMAL2 promoter control in a strain where the first copy has been deleted, permitting analysis of gene function by manipulation of carbon source. CIp10-MAL2p should therefor e provide a useful means for functional analysis of genes in C, albicans, W e have used this strategy with C, albicans DPB2 to demonstrate that the gen e is essential and that loss of function leads cells to adopt a hypha-like morphology as they cease proliferation. Copyright (C) 2000 John Wiley & Son s, Ltd.