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Faculty
 Mary
Jane Osborn
Professor and Head of Microbiology
osborn@nso2.uchc.edu
The problem of organelle biogenesis, and especially the mechanisms by
which individual protein and lipid species are targeted to specific
intracellular membranes, is a major focus of current research in
cellular and molecular biology. This laboratory is interested in
molecular mechanisms of assembly of the outer membrane of Salmonella
typhimurium, with emphasis on the biogenesis of the complex
lipopolysaccharide which is characteristic of this membranous organelle.
Based on biochemical, genetic and immunoelectron microscopic studies, we
have proposed a mechanism for lipopolysaccharide biogenesis which
involves a complex pathway of vectorial transmembrane assembly of the
molecule across the cytoplasmic membrane, followed by translocation to
the outer membrane. A variety of molecular genetic and biochemical
approaches are now being used to test this hypothesis and to analyze
mechanisms of genetic regulation of lipopolysaccharide synthesis.
Current studies have as major aims: 1) isolation and characterization of
mutants specifically blocked in translocation of lipopolysaccharide to
outer membrane; and 2) analysis of the mechanism of positive
transcriptional regulation of genes for biosynthesis of O-antigen chains
of lipopolysaccharide and investigation of the possibility that this
transcriptional control system functions as part of a larger
environmentally regulated control circuit.
Selected Publications:
McGrath, B.C. and M.J. Osborn (1991) Localization of the terminal
steps of O-antigen synthesis in Salmonella typhimurium. J.
Bacteriol. 173:649-654.
Marino, P.A., B.C. McGrath and M.J. Osborn (1991) Energy dependence
of O-antigen synthesis in Salmonella typhimurium. J. Bacteriol.
173:3128-3133.
McGrath, B.C. and M.J. Osborn (1991) Evidence for energy-dependent
transposition of core lipopolysaccharide across the inner membrane of
Salmonella typhimurium. J. Bacteriol. 173:3134-3137. |
