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Janine Trempy
Associate Dean, College of Science
Professor, Microbiology
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RESEARCH:
All organisms are faced with stresses present in natural and human-influenced environments. The most successful organisms are those which can respond to environmental stresses in an efficient and easily controlled manner. One way that an organism can respond to changing growth conditions is to modify the levels and types of enzymes it produces. In bacteria, as in animal cells, protein degradation is an efficient mechanism for the regulated expression of enzymes in response to changing environmental conditions. This regulatory strategy helps the cell develop a rapid response to and recovery from emergency conditions by affecting the stability of proteins. Active proteolysis can regulate an organism's response to its environment in two ways: by activating an otherwise silent enzymatic function or by eliminating enzymatic functions no longer necessary for cell survival.This research program is designed to analyze molecular mechanisms, such as protein degradation, that permit cells to respond to and then recover from environmental stresses. We use changes in temperature and moisture content, exhaustion of nutrients and exposure to chemicals or ultraviolet light as models of environmental stress. This analysis is carried out in both Gram positive and Gram negative bacteria. Bacteria are notorious for their ability to adapt to changing environmental conditions, thus providing an ideal model system to study the responses that permit this adaptation.
In a related study, we are defining signals that trigger the degradation of specific proteins. How are proteins selected for degradation? If proteins do become targets for the proteolytic machinery, is it because they no longer function in an appropriate and useful manner? How does the proteolytic machinery sense that a protein is no longer useful?
Several practical applications have developed from this basic research. We design bacterial strains for probiotic food and dairy uses and develop enzymatic and genetic probes for bacterial strains important to these industries. In a joint project with scientists from Thailand, we investigate the role of stress-induced capsule in Xanthomonas pathogenicity of rice in addition to developing molecular biological tools for this organism. Additionally, we construct bacterial strains, through molecular genetic technologies, for use as cloning hosts by biotechnology industries.