Dr. John Kirby
Assistant Professor
School of Biology
Dr. John Kirby
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Contact information:
- School of Biology
- 310 Ferst Drive
- Cherry Emerson, Room 231
- Atlanta, GA 30332, Mail Code: 0230
- Tel: 404-894-8418
- Fax: 404-894-0519
- Email:
Research Interests
Bacterial Chemotaxis, Motility, and Signal Transduction; Chemosensory Regulation of Gene Expression; Intercellular Communication in Biofilms; Multicellular Development in Prokaryotes.
Current Research
Bacteria alter their behavior and physiology in response to physical and chemical cues within their environments. For example, E. coli swims away from toxins and toward nutrients such as sugars and amino acids using a process known as chemotaxis. Other organisms secrete antibiotics and hydrolytic enzymes as a defense mechanism when competitors are present. Analysis of the signal transduction processes by which cells detect and mediate responses to environmental factors are the subject of investigation in my lab.
Myxococcus xanthus is a bacterium that displays a multicellular life cycle: cells feed vegetatively on other organisms and form complex fruiting structures to produce spores when starved. Both of these processes require pilus-based motility and depend on chemotaxis and complex intercellular signaling. Like many other motile organisms, M. xanthus possesses multiple copies of the chemotaxis genes. While two of the eight paralogous Che systems in M. xanthus (Frz and Dif) appear to directly regulate motility, our research has shown that the Che3 system regulates gene expression via a s54-dependent transcriptional activator. Our findings suggest that at least four of the eight Che systems in M. xanthus are likely to regulate gene expression and that chemosensory regulation of gene expression may be widespread within the Bacteria.