CLONING AND REGULATED EXPRESSION OF THE CANDIDA-ALBICANS PHOSPHOLIPASE-B (PLB1) GENE

Degenerate oligonucleotides (derived from conserved regions of PLB1 ge nes from S. cerevisiae and other fungi) were used to amplify PLB1 homo log fragments from C. albicans and C. tropicalis by using the polymera se chain reaction. The C. albicans PLB1 fragment was then used as a pr obe to clone the full-length gene and to monitor PLB1 mRNA expression. The C. albicans PLB1 gene consists of a 1815-bp open reading frame en coding a putative protein of 605 amino acids. It contains the highly c onserved Gly-X-Ser-X-Gly catalytic motif, found in all lipolytic enzym es, and exhibits significant homology with other fungal PLB1 gene prod ucts (similar to 63% similarity, similar to 45% identity). Blastospore s and pseudohyphae expressed higher levels of PLB1 mRNA than germ-tube -forming cells. TUP1, a general transcriptional repressor, may regulat e PLB1 expression in C. albicans, since PLB1 expression was the highes t in tup1 Delta mutants and did not vary in response to environmental stimuli. Together, these results suggest that expression of the C, alb icans PLB1 gene is regulated as a function of morphogenic transition. (C) 1998 Federation of European Microbiological Societies. Published b y Elsevier Science B.V. All rights reserved.