Understanding microbial C1- metabolism. Despite the great progress that has been made in our knowledge of microbial methane utilization networks, several fundamental questions remain unanswered. Based on available data, complete methane oxidation can be achieved by only three enzymes: MMO, an Xox-type methanol/formaldehyde dehydrogenase, and formate dehydrogenase. However, so far all attempts to reconstruct this machinery in non-methanotrophic hosts have failed, indicating a serious gap in our knowledge of the components involved or in our understanding of how individual parts of the network are organized and cooperate. We combine systems-level approaches with classical genetics and biochemistry to establish key parts of the methanotrophic networks.

Current research projects:

EMSL (PNNL-DOE): Spatial organization of methane oxidation: rediscovering fundamentals. We rarely think about prokaryotic metabolism as a highly structured system with function-dedicated compartments. It is becoming more apparent that a bag-like representation of microbial metabolism is far from complete. A deeper understanding of a bacterial cell requires a thorough systems-level description of the subcellular network organization (enzyme complexes, compartments).  Methane oxidation is not a simple one-enzyme process; it requires a complex network of enzymes that are dedicated to efficient energy recovery/conservation.  The lack of fundamental knowledge of the first steps of the methane oxidation limits our ability to model methane metabolism and interactions among microbial populations in nature, and, hence, our ability to predict factors impacting the environmental cycle of this dangerous greenhouse gas at local or global scales. It also constrains our ability to perform rational metabolic engineering of methane biocatalysis and to develop new sustainable solutions to environmental problems caused by methane emission.  The goal of this research initiative is to gain a comprehensive knowledge of methane-oxidation machinery.  Comparative, high-resolution, quantitative proteomic studies are critical for construction of a comprehensive view of methane metabolism.