Research TopicsDepartment of Veterinary Pathobiology
Ph.D. (1981) Case Western Reserve University
Research Topics
Research Interests
The Biosynthesis of polysialic acid K1 antigen of E. coli is being studied by application of genetic, recombinant DNA, and biochemical methodologies. K1 antigen is an important correlate of pathogenicity in E. coli that cause neonatal meningitis and urinary tract infections. The kps cluster of 10 to 15 genes is responsible for synthesis, assembly and transmembrane translocation of the sialic acid polymer that comprises the capsule of K1 serotypes. We have recently completed a functional description of the kps region and have identified the genes involved in sialic acid synthesis, activation, and polymerization. Other genes involved in polysaccharide assembly and translocation have been mapped. Relevant structural gene products are now being purified with the aid of gene fusion technology. Using these fusions, we have acquired preliminary evidence that the low temperature regulation of polysialic acid biosynthesis is mediated at the transcriptional level. A "temperature-sensing" gene which regulates this control of an important virulence determinant is being sought.
Recently polysialic acid residues have been identified on certain developmentally regulated glycoproteins in the neonatal nervous system. Collaborative studies have been initiated to determine the function of polysialic acid in embryonic and neonatal neural tissue development. These studies will further our understanding of nervous system organogenesis and will begin to describe in molecular terms the mechanisms of neuronal cell-cell interaction. This information may have practical value for understanding nervous tissue regeneration. In related studies, by screening gene libraries in E. coli, we have cloned Vibrio cholerae and Salmonella typhimurium genes that code for secreted neuraminidases. This achievement represents the first successful cloning of bacterial neuraminidase genes. The structural genes have been sequenced and we plan a detailed structure-function characterization of the enzyme. Among other goals, we will attempt to determine the involvement of neuraminidase in cholera pathogenesis. Since neuraminidase is a secreted enzyme, we anticipate that appropriate fusion vectors might allow secretion of proteins that are not normally secreted in E. coli. Computer assisted analysis of neuraminidase gene sequences have revealed several interesting conserved regions that may function in protein folding.
Key Words Recombinant DNA, Gene Expression Systems, Molecular Evolution,
Neurobiology, Host/Parasite Interactions, Fermentation, Microbial Physiology,
Site-Directed Mutagenesis, Membrane Structure and Function, Protein Purification
and Characterization, Protein Processing and Secretion
Current Research Funding NIH