Functional Dynamics and Energy Coupling Mechanisms of Mitochondrial Membrane Proteins

University Of Connecticut, Storrs CT

Investigators

Abstract

INTELLECTUAL MERIT Mitochondria not only produce the vast majority of energy within eukaryotic cells, but also regulate cellular processes such as calcium homeostasis, lipid synthesis, and metabolite transport. The vital functions carried out by this organelle depend directly on the potential energy that is stored across its inner membrane in the form of a proton electrochemical gradient. Characteristic of all energy-conserving membranes, this potential is parsed as an electric field and a difference in proton activity across the lipid bilayer. This project will address two fundamental features of the mitochondrial inner membrane electrochemical potential. First, the changes in membrane protein structure that are driven by alterations in the energized state of the inner membrane will be investigated. Novel, high resolution fluorescence-based approaches will be employed to elucidate the manner in which alterations in the proton gradient and transmembrane electric field differentially change the conformation of a model mitochondria-resident protein. Elucidating the basis of such electromechanical coupling is vital to understanding how proteins in energy-conserving membranes harness the electrochemical potential to perform cellular work. Second, the energetic landscape of the topologically complex inner membrane will be investigated. Using precisely targeted pH-sensing and electrochromic probes to measure localized ion gradients and electric fields, the temporal and spatial heterogeneity of the inner membrane energetic profile will be measured with unprecedented resolution. By challenging the current dogma of electrochemical potential equilibrium across the membrane regions, this work is poised to create a new paradigm for understanding the energetic regulation of processes such as ATP production and local changes in the bilayer structure. These advances in the current understanding of membrane bioenergetics will be made possible by the technical innovations used in this research. BROADER IMPACTS This NSF-sponsored work will involve two teams of researchers in a model designed to promote multidisciplinary interactions and development of leadership in the sciences, emphasizing the involvement of students traditionally underrepresented in the STEM fields. The work will also serve to further develop and expand novel research tools in the construction of model membrane systems and in the process of site-specific polypeptide labeling, all of which will be made available to the scientific community. The education outreach component of this project is based on the Biology Summer Institute series in cooperation with the University of Connecticut Early College Experience Program. This series of modular classroom and laboratory courses offers professional development to teachers from regional high schools, exposing them to advances in research and current scientific topics, which can be integrated into their own curricula during the subsequent academic year. As this program develops, the Institute will be expanded to include summer courses for high school students as well. Taken together, this education outreach will be highly integrated with the research activities of the project. Moreover, the outcomes of this pedagogical outreach model will be disseminated in educational publications and conference workshops as a means of effectively helping to raise scientific literacy of the public.