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Dr. Meredith C. Durmowicz
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Dr. Meredith C. Durmowicz
Department Chair, Biological Sciences and Assistant Professor of Biology
Location: Science Wing - 114
Phone: 443-334-2414
Email Address: f-durmow@mail.vjc.edu
EDUCATION
B.S., Marquette University
Ph.D., The Johns Hopkins University
POSTDOCTORAL RESEARCH, 1998-2003
National Institute on Aging, NIH
Baltimore, MD
My teaching responsibilities have included General Biology (BIO 113), Microbology (BIO 203), the biology half of an introductory chemistry/biology course for freshmen nursing and nursing intent majors (SCI 111) and the Senior Research Project courses (BIO 450/460 and CHEM 450/460).
My research interests focus on the networks that control gene expression in both eukaryotic and prokaryotic organisms. Here on campus, my work involves studies of the nitrogen-fixing symbiotic bacterium Bradyrhizobium japonicum. This bacterium lives in symbiosis with soybean plants, improving growth and survival by providing this important crop plant with a ready source of nitrogen.
The nitrogen fixation reaction, while much more efficient than industrial production of ammonia, is not totally biologically efficient, since hydrogen is produced as a by-product. In B. japonicum, a nickel-containing hydrogenase enzyme functions to improve the efficiency of symbiotic nitrogen fixation by recycling the hydrogen that is produced. This enzyme also functions when the bacterium is in the free-living state, most likely to help it survive poor soil conditions. Among the many bacterial signal transduction networks that activate the transcription of target genes in response to metals, the regulation of hydrogenase synthesis in B. japonicum is of particular interest because, in addition to its beneficial role during symbiosis, the hydrogenase system is currently the only one in which nickel-dependent transcriptional regulation in both free-living and symbiotic conditions has been demonstrated.
In my previous work, we identified the HoxA protein as the DNA-binding protein that directly controls hydrogenase transcription under free-living conditions. The identity of the sensor protein or proteins that interact with HoxA and the mechanisms by which these factors respond to hydrogen, oxygen, and nickel levels are the subjects of some of my studies. In the symbiotic state, hydrogenase expression is linked to control of nitrogen fixation by proteins in the FixLJ-FixK regulatory cascade. We have shown that the FixK2 protein is responsible for the regulation of symbiotic hydrogenase expression, though the exact mechanisms and signals have yet to be identified.
We are also studying a chemically generated mutant of B. japonicum that exhibits constitutively active hydrogenase activity as well as increased levels of other oxygen-responsive proteins, suggesting that a more global regulatory mechanism may play a role in the control of hydrogenase expression.
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