Brian Hammer, Assistant Professor
Ph.D., Microbiology and Immunology, University of Michigan Medical School, 2001
M.S., Aquatic Ecology, University of Michigan School of Natural Resources & Environment, 1995
Phone: 404-385-7701
Fax: 404-894-0519
Office: (CE) 223
Research Interests
Microbiology, quorum sensing, regulatory small RNAs, signal transduction, host-pathogen interactions, microbial biofilms
Overview
Research in my lab focuses on the bacterial pathogen Vibrio cholerae, a common inhabitant of marine environments and also the causative agent of the fatal diarrheal disease cholera. In particular, we study a process of cell-cell communication called quorum sensing, which is used by V. cholerae and other bacteria to communicate using chemical signaling molecules called autoinducers (AIs). Because the extracellular concentration of the AIs increases as a function of population density, quorum sensing allows bacteria to coordinate gene expression on a population-wide scale and thereby behave like multicellular organisms. In V. cholerae, AI information is funneled internally through a signal transduction circuit that impinges on the transcription of multiple small regulatory RNAs (sRNAs). Using a combination of genetics, bioinformatics, and genomics we have recently identified the molecular mechanism that explains how base-pairing of the sRNAs with target mRNA can both activate as well as repress expression of target genes. Importantly, we revealed that this sRNA signaling pathway is conserved in Vibrios isolated from both clinical and marine settings. The goal of our work is to reveal how quorum sensing enables V. cholerae to adapt to and exploit pathogenic and environmental niches that it inhabits.
Selected Publications
[Complete list of publications]
Hammer BK & BL Bassler. 2008. Multiple HD-GYP proteins that are activated by quorum sensing in the El Tor biotype of Vibrio cholerae degrade cyclic di-GMP and alter biofilm formation. In preparation.
Hammer BK & BL Bassler. 2008. Signal integration in the Vibrio harveyi and Vibrio cholerae quorum-sensing circuits, in Chemical Communication among Bacteria, ASM Press. 323-332.
Hammer BK & BL Bassler. 2007. Regulatory small RNAs circumvent the conventional quorum sensing pathway in pandemic Vibrio cholerae. Proc. Natl. Acad. Sci. USA. 104:11145-11149.
Hammer BK & BL Bassler. 2003. Quorum sensing controls biofilm formation in Vibrio cholerae. Mol. Microbiol. 50:101-114.
Hammer BK, ES Tateda & MS Swanson. 2002. A two-component regulator induces the transmission phenotype of stationary phase Legionella pneumophila. Mol. Microbiol. 44:107-118.
Swanson MS & BK Hammer. 2000. Legionella pneumophila pathogenesis: A fateful journey from amoebae to macrophages. Ann. Rev. Microbiol. 54:567-613.
Hammer BK & MS Swanson. 1999. Coordination of Legionella pneumophila virulence with entry into stationary phase by ppGpp. Mol. Microbiol. 33:721-731.
Hammer B & EF Stoermer. 1997. Diatom-based interpretation of sediment banding in an urbanized lake. J. Paleolimnol. 17:437-449.
Nelson D, Kuppermann N, Fleisher GR, Hammer B, Thompson CM, Garcia CT, Novitsky TJ, Parsonnet J, Onderdonk A, Siber GR & Saladino RA. 1995. Recombinant endotoxin neutralizing protein improves survival from Escherichia coli sepsis. Crit. Care Med. 23:92-98.
Saladino R, Garcia C., Thompson C., Hammer B, Parsonnet J., Novitsky T., Siber G & Fleisher G. 1994. Efficacy of a recombinant endotoxin neutralizing protein in rabbits with Escherichia coli sepsis. Circ. Shock. 42:104-110.