We have established the chemical structure of (+)-bassianolone (3), the antimicrobial compound precursor of cephalosporolides E and F, and that of the furan metabolite 4 from the entomopathogenic fungus Beauveria bassiana.

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Candida albicans is an opportunistic fungus that is part of the normal microflora commonly found in the human digestive tract and the normal mucosa or skin of healthy individuals. However, in immunocompromised individuals, it becomes a serious health concern and a threat to their lives and is ranked as the leading fungal infection in humans worldwide. As existing treatments for this infection are non-specific or under threat of developing resistance, there is a dire necessity to find new targets for designing specific drugs to defeat this fungus. Some authors reported the presence of the transglutaminase activity in Candida and Saccharomyces, but its identity remains unknown. We report here the phenotypic effects produced by the inhibition of transglutaminase enzymatic activity with cystamine, including growth inhibition of yeast cells, induction of autophagy in response to damage caused by cystamine, alteration of the normal yeast division pattern, changes in cell wall, and inhibition of the yeast-to-mycelium transition. The latter phenomenon was also observed in the C. albicans ATCC 26555 strain. Growth inhibition by cystamine was also determined in other Candida strains, demonstrating the importance of transglutaminase in these species. Finally, we identified enolase 1 as the cell wall protein responsible for TGase activity. After studying the inhibition of enzymatic activities with anti-CaEno1 antibodies and through bioinformatics studies, we suggest that the enolase and transglutaminase catalytic sites are localized in different domains of the protein. The aforementioned data indicate that TGase/Eno1 is a putative target for designing new drugs to control C. albicans infection.

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Different techniques released from the wall of Candida albicans mycelial cells high molecular weight mannoprotein materials with different levels of complexity. SDS solubilized among others one protein of 180 kDa which reacted with a monoclonal antibody (MAb) specific of a O-glycosylated protein secreted by regenerating mycelial protoplasts [Elorza et al. (1989) Biochem Biophys Res Commun 162:1118-1125]. Zymolyase, chitinase and beta-mercaptoethanol, released different types of high molecular highly polydisperse mannoprotein materials (greater than 180 kDa) that also reacted with the same MAb. These materials had N-glycosidically linked sugar chains, in addition to the O-glycosidically bonded sugars, as their molecular masses were significantly reduced by Endo H digestion. Besides, the specific materials released by either zymolyase or chitinase seemed to be the same throughout the process of germ tube formation. Transmission electron microscopy of thin sections of cells and walls showed that mannoproteins and chitin are evenly distributed throughout the entire cell wall structure.