Faculty

Timothy R. Hoover, Ph.D.
Associate Professor of Microbiology, Associate Head of Microbiology, and Undergraduate Coordinator
Ph.D. (1988) University of Wisconsin-Madison

Address: Department of Microbiology
548 Biological Sciences Building
Athens, GA 30602-2605
Phone: (706) 542-2675
E-mail: trhoover@uga.edu
COS CV: http://myprofile.cos.com/hoovert44
PubMed: hoover tr

Research Interests:
Helicobacter pylori is a bacterial pathogen that causes a variety of stomach diseases in humans, including chronic gastritis, peptic ulcer disease and gastric cancer. To colonize the gastric mucosa H. pylori must be motile via a cluster of polar flagella. Flagellar biosynthesis in H. pylori involves a transcriptional hierarchy that requires all three sigma factors found in the bacterium (RpoD, RpoN and FliA) and over 40 structural and regulatory genes. This transcriptional hierarchy is coordinated with flagellar assembly through the activity of the flagellar protein export apparatus, a type III secretion system responsible for transporting many of the flagellar proteins across the cell membrane. Mutations in genes encoding export apparatus components inhibit transcription of RpoN-dependent and FliA-dependent flagellar genes. Current work in the lab is directed at identifying the mechanism by which the export apparatus controls expression of these flagellar genes. A second project in the lab focuses on RpoN (σ54), an alternative σ factor required for transcription of genes involved in diverse cellular functions, such as nitrogen metabolism, solute transport, flagellar biogenesis and hydrogen evolution. σ54-RNA polymerase holoenzyme (σ54-holoenzyme) binds the promoter to form a stable closed complex but cannot form an open complex until it is engaged by an activator. Bacteria often have several different σ54-dependent activators, each targeting a specific set of genes. Using Salmonella typhimurium as a model, we are analyzing promoters to identify sequences important for recognition by σ54-holoenzyme. In addition, we are analyzing intragenic ‘promoter-like’ sequences in the S. typhimurium genome which we found to be recognized by σ54-holoenzyme in vivo. We postulate that these sequences have novel regulatory roles or serve as ‘storage’ sites for σ54-holoenzyme that allow the cell to respond rapidly to conditions that trigger expression of σ54-dependent genes.

Publications:
P. Brahmachary, G. Wang, S.L. Benoit, M.V. Weinberg, R.J. Maier and T.R. Hoover. 2008. The human gastric pathogen Helicobacter pylori has a potential acetone carboxylase that enhances its ability to colonize mice. BMC Microbiology 8:14.

L.L. Beck, T.G. Smith and T.R. Hoover. 2007. Look, no hands! Unconventional transcriptional activators in bacteria. Trends Microbiol. 15:530-537.