STRUCTURE ANALYSIS OF KEY DRUG DESIGN TARGET ENZYMES FROM HUMAN PATHOGENS. Christopher M. Bruns¹, Andrew S. Arvai¹, Andrew J. Nowalk², Timothy A. Mietzner², Duncan E. McRee¹, and John A. Tainer¹. ¹Department of Molecular Biology, The Scripps Research Institute, 10666 N. Torrey Pines Rd., La Jolla, CA USA 92037; ²Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA USA 15261

Two proteins that represent promising drug design targets against human pathogens are the major ferric iron binding protein (FBP) from Neisseria and Haemophilus, and glutathione-S-transferase (GST) from Schistosoma. These proteins are both members of structural families for which several crystal structures are already known, permitting rational design of inhibitors specific for particular family members.

FBPs from two species of pathogenic bacteria have been crystallized. FBP crystals from Haemophilus influenzae (which causes many infections, including meningitis) diffract X-rays to 1.6 Å resolution. Anomalous scattering from these crystals unambiguously reveals the position of the iron atom at the active site. Crystals of FBP from Neisseria gonorrhoeae (which causes gonorrhea) diffract to 2.8 Å. Crystallographic determination of these protein structures is underway.

The crystal structure of GST from Schistosoma japonicum has previously been determined, both in native form and in complex with praziquantel, the leading drug used to treat schistosomiasis (McTigue et al 1995). We are working to evaluate other potential inhibitors by X-ray crystallography.

Difficult sequence and structure alignment problems encountered during the analysis of these two families of proteins have motivated the development of a general purpose sequence alignment program designed to incorporate tertiary structure information into traditional sequence alignment methods. The progress of these studies will be discussed.

(1) McTigue, M;Williams, D; and Tainer, J (1995) J.Mol.Biol. 246:21-27