Control of Sulfite Reductase Activity via Structural Flexibility and a Push-Pull Mechanism for Electron Transfer

Florida State University, Tallahassee FL

Investigators

Abstract

This work aims to discover fundamental mechanisms for how bacteria metabolize sulfur by exploring the structure and function of an enzyme known as sulfite reductase. The topic is of particular importance owing to the rise of environmental pollution in the form of toxic sulfur byproducts from commercial pig farms that leech into the environment due to recent flooding in the southern United States. The proposal will help train undergraduate and graduate-level researchers in the scientific methods and techniques in which the laboratory excels. The results from these experiments will inform our understanding of the basic science of sulfur metabolism as well as provide insights into technological advances in bioremediation of toxic sulfur compounds. The experiments outlined in this proposal aim to answer three questions: 1) how does sulfite reductase function as a macromolecular oxidoreductase machine? 2) how do the two sulfite reductase subunits interact to allow for efficient six electron transfers? 3) from where do the protons come to balance the electron transfer reactions? The experiments will use a variety of biophysical techniques, including small angle neutron scattering, neutron diffraction, X-ray diffraction, and cryogenic electron microscopy to comprehensively analyze the complex interactions and conformations this enzyme adopts. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.