NEW PERSPECTIVE ON ACETATE AND ONE-CARBON METABOLISM IN THE METHANORCHAEA: CARBONIC ANHYDRASE

Carbonic anhydrases catalyze the reversible hydration of carbon dioxide to bicarbonate. Prokaryotes encode three independently evolved classes (alpha, beta, and gamma). Although wide-spread in prokaryotes, only three gamma-class enzymes have been biochemically characterized and the physiological functions have not been investigated. This grant proposes to determine the physiological function of gamma-class carbonic anhydrases from Methanosarcina acetivorans to gain a better understanding of the conversion of acetate to methane by this species that is key to the formation of methane from waste and renewable biomass (biomethanation) as an alternative to fossil fuels. A genetic approach will be taken to ascertain the role of carbonic anhydrases in the transport of acetate into the cell. Formate production and utilization is another important process in the process of biomethanation. A parallel genetic approach will be taken to determine the role of carbonic anhydrases in the transport of formate into the methane-producing species Methanococcus maripaludis. The results are expected to translate to the physiological function of a diversity of anaerobes involved in biomethanation.