Iron(III) and arsenate-reducing bacteria are known to promote the mobilization of arsenic from contaminated sediments into aquifers. Consequently, populations consuming water sources where these metal-reducing bacteria are active may be at increased risk for developing cancer and skin lesions due to elevated levels of arsenic. This research will develop a molecular-mechanistic understanding of arsenate respiratory reduction, which is a major biological process thought to promote arsenic mobilization. The goal of the project is to determine how CymA interacts with other redox components predicted to occur in the anaerobic electron transport chain of arsenate-reducing Shewanella species. The specific aims are to: (1) test the hypothesis that CymA exhibits menaquinol binding activity and (2) test the hypothesis that CymA interacts with the arsenate respiratory reductase, ArrAB. Menaquinol binding of CymA will be determined using menaquinol analogs that can be monitor by their spectroscopic properties. In vivo protein-protein interactions of CymA with ArrAB will be investigated using frequency resonance energy transfer (FRET) methods and CymA and ArrAB proteins fused with fluorescent proteins known to exhibit FRET signals. Results from this study will have direct applications to understanding similar interactions with downstream pathways for nitrate, fumarate, and iron oxide metabolisms. This research will provide new insight into environmental investigations of the underlying mechanism of microbial-mediated mobilization of arsenic. The broader impacts of the work will include promoting the education of undergraduate and graduate students. Students will receive hands-on training in anaerobic microbiology, preparation of media, and methods for analyzing the end products of respiration.
