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Office: 3-632 BSBIowa City, IA 52242 Phone: +1 319 335 7818 Email: john-kirby@uiowa.edu
Office/Lab: 3-632 BSBIowa City IA, 52242 Phone: +1 319 335 7818
Office/Lab: 3-615D BSBIowa City IA, 52242 Phone: +1 319 335 7938
Web: Kirby Lab Website
BS, Biochemistry, University of Illinois Urbana-Champaign, 1992PhD, Biochemistry, University of Illinois Urbana-Champaign, 1998Post-Doc, Molecular Cell Biology, University of California, Berkeley, 2002
Primary: Microbiology
chemosensory regulation of gene expression and motility and physiology in Myxococcus xanthus, mechanism of chemotaxis in Bacillus subtilis, microbiome of the human nasopharynx, virulence in non-typeable Haemophilus influenzae
We are interested in chemosensory signal transduction systems that regulate motility and development in the bacterial model organisms, Myxococcus xanthus and Bacillus subtilis. Chemosensory systems are chemotaxis-like two component systems that regulate a variety of cellular functions ranging from flagellar based motility to sporulation.
Chemosensory regulation of Motility, Physiology & Development in M. xanthus. Analysis of signal transduction systems that allow cells to detect and mediate responses to environmental factors, including neighbor contact, is the major subject of investigation in our lab. M. xanthus is a soil bacterium that displays a multicellular life cycle. Cells feed on other organisms and form complex fruiting structures, culminating in spore production when starved. These processes require Type IV pilus-based motility and depend on chemotaxis and complex intercellular signaling. M. xanthus utilizes over 120 two-component systems, including eight homologous chemosensory signaling pathways to regulate its complex lifestyle. While some of these che homologs are involved in the regulation of motility and predation, others have been shown to affect a variety of cellular functions including gene expression and carotenoid biosynthesis. Our projects focus on the chemosensory regulation of gene expression, lipoprotein-dependent stress responses, type IV pilus assembly, and membrane composition.
Mechanism of Chemotaxis in Bacillus subtilis. Analysis of the B. subtilis chemotaxis system focuses our work on CheC, CheD, and CheV. Homologs to these proteins are not found in E. coli but are present in the majority of known chemotactic Bacteria and Archaea. Our projects include the characterization of CheD deamidase activity and HAMP domain interactions, targets and regulation of CheC phosphatase activity, and regulation of signaling by the unique receptor-kinase coupling protein, CheV. The broad distribution of CheC, CheD and CheV identified by genome sequencing allows us to conclude that B. subtilis is the best paradigm for the study of chemotaxis in prokaryotes.