Dr. Theresa M. Koehler
The University of Texas Health Science Center at Houston
McGovern Medical School
Department of Microbiology and Molecular Genetics
Our research interests center on host-pathogen interactions, with an emphasis on the physiology and genetics of the Bacillus cereus group species: B. anthracis, the causative agent of anthrax; B. thuringiensis, a Lepidoptera pathogen; and B. cereus, a food-poisoning agent and opportunistic pathogen of humans. These species are endemic soil bacteria with complex signaling pathways for lifestyles within and outside of host organisms. They are developmental microbes and cell state plays a key role in bacterial survival and transmission. The genome sequences and overall physiology of the B. cereus group species are remarkably similar. A few crucial differences, some related to plasmid content, others associated with key regulatory genes, result in the distinct diseases caused by these bacteria. We are focused on molecular mechanisms controlling expression of secreted virulence factors of B. anthracis. The model for virulence gene control in B. anthracis is of growing complexity and includes numerous trans-acting regulators. The most critical and far-reaching is AtxA, a pleotropic regulator that affects B. anthracis physiology in host and non-host environments. AtxA is the archetype for an emerging family of transcriptional regulators that are controlled by the phosphoenolpyruvate:carbohydrate phosphotransferase system, a central processing circuit that allows adaptation to changes in availability of specific carbon sources. The technical repertoire of our laboratory includes molecular genetics, protein biochemistry, and animal models for infection. Tutorial students are matched with a senior student or postdoctoral fellow to complete a project involving nucleic acid methods, genetic screens and selections, protein purification, gene expression assays, and/or microscopy.