Fly Enzymes: Potential Bioremediators?
by Mika Pringle Tolson
UC TSR&TP Trainee Susan Wei
Susan Wei found her ideal research project as a first year doctoral student while going through her laboratory rotations in the Department of Medical Microbiology and Immunology at UC Davis. Says Wei, "Given my previous research experiences, it was exactly what I was looking for." As an undergraduate in biochemistry at UC Riverside, she studied fertilization in frogs, but she thought, "Great, this is neat, the biology of the frog, but how is it important or significant to the betterment of life at large?" She knew she wanted to "do something that was applied" that she could possibly "see the results of in a few years." Other students in her advisor's lab had been cloning and studying glutathione S transferases (GSTs) in houseflies, but they had not yet identified the isozymes responsible for insecticide resistance. GSTs are a group of enzymes, ubiquitous in all organisms, that are very important in the detoxification function of cells and organisms; they bind to toxic chemicals and conjugate them into a non-toxic chemical form. Wei began studying GSTs last year and identified a new one, GST-6, which highly correlated with the characteristics of an insecticide degrading GST. With her graduate student fellowship from the TSR&TP, she has isolated the gene for GST-6 and is now working on expressing it in the bacterium Esherichia coli. Once the gene is expressed in the bacterium, she will test for bacterial growth with pesticides. Then she will mutate the gene by forced evolution to alter the GST's substrate domain so that it will accept and degrade other toxic chemicals. Beyond developing this bacteria-based system for engineering and generating novel GSTs, the implications of this research are enormous. The most immediate application is the bioremediation of sites contaminated with insecticides. Wei explains, "We're trying to get these enzymes to express in bacteria so that bacteria can essentially eat insecticides. A soil bacterium having such funtions could be very useful for toxic cleanup." Not only may this work be important for environmental cleanup, but it has potential applications for human health as well. "These types of enzymes are being investigated as possible antidotes for chemical poisonings", says Wei. Besides the practical applications of her research on GSTs, she will also make significant contributions to basic science by furthering knowledge of the relationship of GSTs to resistance in insects, the structure and function of GSTs, and the metabolic requirements of E. coli. Following the completion of her project, Susan Wei will be looking into postdoctoral positions, and eventually she'd like to continue her research in an academic or an industrial environment.
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