Dynamic expression of cell wall proteins of Candida albicans revealed by probes from cDNA clones

Abstract

Five cDNA clones were selected from the positive clones detected by screening a germ tube expression library constructed in lambda gt11 with rabbit antisera raised against cell wall extracts of Candida albicans. The selected clones were amplified and used to obtain affinity purified antibodies by eluting from the expressed proteins that had been previously transferred onto nitrocellulose discs. The antibodies obtained were used as probes in immunoblots of the cell wall extracts separated by denaturing polyacrylamide electrophoresis. A single protein band was detected for each clone. Detection of products of the cloned sequences varied according to the extraction procedure and/or cell morphology. These products included bands exhibiting apparent molecular weights of 40, 58, 68 and 70 kDa present in beta-mercaptoethanol (beta ME) extracts from both yeast and germ tubes, and a 30 kDa beta ME extracted protein specific for germ tubes. The expression of these products at the cell surface was confirmed by indirect immunofluorescence. Expression of the mRNAs of the different cDNA clones varied according to growth- and morphology-related factors and showed no direct correlation between expression and presence in the cell wall. These observations suggest that complex mechanisms are involved in the regulation and expression of cell surface components of C. albicans.