RUI: Protein Tyrosine Oxidations to Maintain Cellular Redox State

Calvin University, Grand Rapids MI

Investigators

Abstract

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. David Benson from Calvin College to investigate how and why some proteins become antioxidants. Antioxidants, in a variety of nutritionally valuable foods, are small molecules that get oxidized rather than cellular components such as proteins, membranes, or DNA. A new class of antioxidants-proteins modified to contain antioxidants while still being attached to the protein-dramatically decreases the oxidation of the modified protein. The experimental procedures will detail how these protein modifications form and function in minimizing oxygen addition to themselves or other proteins by using a variety of biochemical, ultraviolet absorbance, fluorescence, and mass spectrometric detection methods. This work will be performed while training undergraduates, at Calvin College and Grand Rapids Community College, on how to perform research in preparation for working in a highly skilled technical workforce. The findings of this work will contribute to better understanding the resilience of biological systems while also preparing the next generation of the scientific workforce. This work will focus on tyrosine post-translational modifications that can be reversibly oxidized under physiological conditions. These modified tyrosines are best known to participate in redox catalysis. The role of one modified tyrosine, 3'-(S-cysteinyl)-tyrosine (Cys-Tyr), will be studied in aerotolerance of a gut bacterium (Bacteroides fragilis), minimizing protein oxidation of a protein that regulates cellular cysteine concentrations (rat cysteine dioxyngease), and potentially modulating ubiquitination of proteins. A recently developed fluorescence assay will be used to rapidly determine Cys-Tyr reaction yield under a variety of conditions and correlate changes in protein function with Cys-Tyr formation. Due to the reversible oxidation chemistry displayed by Cys-Tyr, and other modified tyrosines, the hypothesis is that an anti-oxidant role for Cys-Tyr may be established. This role would be important as covalent-attachment localizes anti-oxidant function to a protein and provides a new protein function in response to oxidative stress.