Isolation and identification of a 92-kDa stress induced protein from Candida albicans

It was previously shown that the presence of estrogen enhances survival of Candida albicans under heat and oxidative stresses. A 92-kDa protein is inducible by heat shock and estrogen in C. albicans. Previous studies have described this protein as hsp90 because of its molecular size and heat inducibility as seen on electrophoretic gels and Western blots. In this study, ion exchange, hydroxyapatite and size exclusion chromatography were used to isolate a 92-kDa-protein band. The N-terminal sequence of isolated protein blotted onto a PVDF membrane was determined to be V-Q-S-?-V-L-G-F-P-R. This sequence is homologous to the N-terminal sequence of the MET6 gene product, cobalamin-independent methionine synthase, from Saccharomyces cerevisiae. The results of this study suggest that a cobalamin-independent methionine synthase homolog is inducible by heat and estrogen in C. albicans. This study also suggests that Candida hsp90 is more likely to exist as an 82-kDa protein as predicted by a previously described cDNA and not as a 92-kDa protein as reported in the literature.