Molecular and Genetic Controls Regulating Bacterial Arsenite Oxidation

Montana State University, Bozeman MT

Investigators

Abstract

Unacceptable health risks associated with elevated arsenic concentrations in drinking water supplies in the United States and epidemic-level arsenic poisoning in countries worldwide (e.g. Bangladesh) have elevated national and global interest in environmental processes controlling the mobility and fate of arsenic in soil and water. Microbial biochemical transformations of arsenic are critically important to controlling its transport, bioavailability, and toxicity in nature. Bacteria will oxidize arsenite [As(III)] or reduce arsenate [As(V)] for either detoxification purposes or to generate cellular energy. However, understanding of the biochemistry and genetics underlying these transformations is overly simplistic, particularly in terms of how microorganisms sense or oxidize As(III), and thus constrains an ability to understand arsenic behavior in the environment. Current studies indicate that two-component signal transduction and quorum sensing co-regulate the aox genes that encode key regulatory and functional activities essential to As(III) oxidation. The focus of this project is to understand how the expression of the aox genes is controlled by these regulatory systems, with the specific aims being to: i) identify sensor and signal transduction components of the two-component proteins AoxS and AoxR; ii) determine how the As(III) signal is perceived; and iii) identify the quorum sensing metabolite(s) involved. In terms of broader impact, the results of this study should be applicable to the field of environmental health and are projected to be of value for guiding remediation efforts aimed at manipulating microbe-As interactions in certain agricultural, mine reclamation, and municipal water treatment settings. The research will also impact human resource development by providing training opportunities for a Ph.D. student and undergraduate research interns, with the latter targeting Native American students. Furthermore, knowledge generated from this study will be integrated into the undergraduate and graduate courses taught by the PIs, as well as at participant-appropriate levels in education-outreach activities that involve grade school, high school, and scientific-lay adult audiences.