ISOLATION OF mRNA 5'-CAPPING ENZYME FROM THE PATHOGENIC FUNGUS CANDIDA ALBICANS AND SCREENING FOR SPECIFIC INHIBITORS OF THE ENZYME

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We isolated mRNA 5' capping enzyme gene from the pathogenic fungus Candida albicans. The enzyme which was expressed in E.coli and purified has an activity for mRNA 5' guanylyltransferase and was used for screening of the specific inhibitors. 2 candidates inhibitors were selected. We also isolated a human cDNA for mRNA 5' capping enzyme from HeLa cDNA library. This cDNA encoded both mRNA 5' triphosphatase at 5' half and mRNA 5' guanylyltransferase at 3' half unlike C.albicans mRNA 5' capping enzyme encodes only mRNA 5' guanylyltransferase. From these results, it was suggested that mRNA 5' capping enzyme of C.albicans has a different conformation from that of human despite the enzymes of C.albicans and human have the same activity, and mRNA 5' capping enzyme is a feasible target for drug discovery. X-ray crystallography is underway using purified enxyme from E.coli containing mRNA 5' guanylyltransferase of Schizosaccharomyces pombe.To search for more insight about C.albicans, we investigated the enzymes for beta-glucan synthesis. beta-glucan is a component of cell wall in yeast. We demonstrated that CaKRE6 gene encode beta-1,6-glucan (one of beta-glucan) synthesis, is essential for growth, and CaGSC1, CaGSL1, CaGSL2 gene products are needed for beta-1,3-glucan synthesis. Furthermore, CaSLN1 and CaNIK1 encode histidine kinase which was not found in higher eukaryotes and the both gene products are need for pathogenicity in C.albicans.