This EArly-concept Grant for Exploratory Research (EAGER) award through the Chemistry of Life Processes Program and Chemical Catalysis Program in the Division of Chemistry is funding Dr. Eric Schelter of the University of Pennsylvania to study the electronic structure of functional model complexes of the active site of the first rare earth-containing metalloenzyme and to synthesize new efficient catalysts for the dehydrogenation of alcohols. It has been recently discovered that M. fumariolicum SoIV, an organism found in the Sofatara Crater in Italy, requires rare earth metals in order to grow. This surprising finding marks the first time that any rare earth elements have been found to be necessary for life. It has also been recently determined that the organism possesses a cerium atom in a key enzyme used to convert methane into a food source for the organism. This project is focused on determining exactly how the cerium center does this and what the role of the rare earth elements are in keeping these microbes alive. This work will have a broad impact on our understanding of the basic features of life and what is required for life to be sustained, even in extremely harsh environments. Graduate students trained through this project will acquire unique and diverse skills at the interface of bioinorganic chemistry and chemical catalysis. The findings of the project will be communicated through outreach programs targeted toward high school students and the general public. Underrepresented groups including women graduate students, an African American graduate student, a visiting African woman scientist and a Latino postdoctoral associate will benefit from support of the project.
Recent studies have shown that the methylotrophic M. fumariolicum SolV has an essential growth requirement for the rare earth metals La-Gd. The methanol dehydrogenase enzyme of M. fumariolicum SolV was determined to have a cerium cation in its active site. This surprising finding marked the first instance that rare earth elements (RE = La-Gd, Sc and Lu) were shown to have an essential biochemical role. The central hypothesis of this application is that the metal redox activity of Ce can be used to evaluate the electronic structure of the active site, that Ce-quinone complexes will similarly induce methanol dehydrogenation in model complexes, and that the strong Lewis acidity of RE cations enable fast and unique reactivity for the cerium methanol dehydrogenase. The team will test the hypothesis through a combination of model complex synthesis, electrochemistry and density functional theory studies. The overall goals of the research are to determine the electronic structure of the cerium active site and to synthesize functional model complexes of the enzyme that catalyze the dehydrogenation of alcohols.
