We are working in the area of molecular biology of pathogenic yeast using Candida albicans as a model system with an aim to understand the nature of virulent factors associated with the medically important yeast. Candida albicans, is the most pathogenic of Candida species. It is a serious agent of infection particularly in immuno compromised patients. The delicate balance between the host and the otherwise normally commensally fungus, turn into a parasitic relationship, resulting in the development of infection is called candidiasis. It is believed that for C. albicans to become invasive, a change from yeast to hypha is important. Yeast to hypha conversion occurs through an intermediate germ tube stage. The germ tube leads to hyphae formation. N-acetylglucosamine (GlcNAc) is utilized by the pathogenic strains of C. albicans. GlcNAc also induces change in cellular morphology in C. albicans. Morphogenetic changes like hyphae and pseudohyphal growth enables to propagate into the host tissue as a preliminary manifestation of invasion and spread of pathogens. To elucidate the role of GlcNAc in pathogen city, NAG1 has been cloned in our laboratory. GlcNAc transcriptionally induces NAG1. Sequence analysis of a 4 kb genomic clone containing NAG1 indicates that this gene is part of a cluster containing two other genes of the GlcNAc catabolic pathway: DAC1 (GlcNAc-6- phosphate deacetylase) and HXK1 (GlcNAc kinase). Clusters of functionally related genes are general features of prokaryotes and are less prevalent in eukaryotes. In E. coli the amino sugar pathway genes are also organized in clusters and possibly have a common regulatory mechanism. This is the first report of a gene cluster in Candida (Proc. Natl. Acad. Sci, USA 97: 14218-14223, 2000). Interestingly, attenuation of virulence occurs by disruption of this pathway (Infection and Immunity, 69 (12), 7898-7903, 2001).