Beta carbonic anhydrases (beta-CAs) are bicarbonate-utilizing enzymes that are essential for optimal growth in many bacteria and yeast, including some disease-causing microorganisms. Bacterial beta-CA has a unique non-catalytic bicarbonate binding site that is thought to be central to the regulation of this enzyme. This site presents a potentially attractive target without human counterpart for antimicrobial agents. The molecular basis of regulatory mechanism is not known. This research project will use methods of biophysical chemistry (including enzyme kinetics and visible spectroscopy) and structural biology (X-ray diffraction) to reveal the molecular mechanism of this regulatory site. This knowledge could be exploited in the future to design molecules to specifically interfere with the function of this enzyme for anti-microbial purposes, or to gain insight into the metabolic role of the enzyme in bacteria and other microorganisms in which it is present. There are several broader impacts of the research project, one of which is the involvement of undergraduate students in research projects that provide training in advanced, current praxis in protein chemistry and structural biology. A high percentage of these students are expected to enter into advanced degree programs in the physical and life sciences, and ultimately the domestic scientific work force. In addition, a post-doctoral fellow with an interest in entering the undergraduate education community will be trained in biophysical chemistry and structural biology. Written laboratory guides appropriate for involving undergraduates or other novice investigators in modern praxis in protein engineering and X-ray crystallography will be updated and freely disseminated to the scientific community. Finally, the funding of critical research equipment replacement and upgrades will significantly enhance the biophysical chemistry research infrastructure at Colgate University.
This research grant supported investigations of the molecular structure and biological function of beta-carbonic anhydrase, an enzyme involved in the cellular trafficking of carbon dioxide. This protein is essential for growth of many bacteria, including disease-causing organisms. Using X-ray crystallography and fast kinetics techniques, we uncovered key details of how beta-carbonic anhydrase is regulated by bicarbonate ion, which the enzyme produces from carbon dioxide. By specifically altering the structure of the protein using site-directed mutagenesis, we were able to disable this regulatory function. The results of this research (1) suggest possibilities for interrupting the function of this essential bacterial protein in disease-causing bacteria, (2) provide clues as to how the regulatory feature of this protein may have arisen during evolution from non-regulatory versions of the enzyme, and (3) provide new insights into enzyme regulation for this specific case and in general. This work was disseminated in the form of 4 peer-reviewed research publications that included 9 different undergraduate student co-authors, and five presentations at national professional meetings. In broader impacts of this research, 6 undergraduate students obtained training and education in modern methods of biochemistry research during the summer months, not including 6 additional students during the academic year. Additionally, a postdoctoral fellow was trained and is now teaching and conducting research with undergraduates as a full-time faculty member at a primarily undergraduate institution. We have also freely shared our research methods on a publicly available web site.
