In Vitro Screen for Fungal Glucan Synthase Inhibitors

Fungi are medically and economically very important, contributing to waste, spoilage and disease. Treatment of human fungal disease, especially in immunodeficient patients suffering from Acquired Immunodeficien- cy Syndrome, is hampered by the virtual lack of clinically useful drugs. Filamentous fungal morphogenesis and growth are the direct result of polysaccharide polymers and other materials being sequentially deposited at each hyphal apex, leading to the formation of a mature cell wall. Cell-wall assembly results in a wall containing chitin, beta(1-3) glucan, and other beta- and alpha-linked glucans, proteins and lipids. Perhaps the key step in fungal cell-wall assembly is the synthesis of beta (1,3) glucan, and its subsequent incorporation into the cell wall. Although there are a number of known glucan synthase inhibitors, each suffers from a variety of flaws that precludes their clinical use. We will develop a high-throughput, sensitive, specific screen for inhibitors of beta(1,3) glucan synthase activity. This screen can be used to identify novel inhibitors for eventual therapeutic use.