Analyzing Mrc-dependent and -independent energy metabolism in Methanosarcina acetivorans

• Applicant: Professor Dr. Michael Rother
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548692950

Methanogenic archaea (methanogens) play a pivotal role for the global carbon cycle. Through the energy metabolism they employ, methanogenesis, which generates the potent greenhouse gas methane, methanogens are directly linked to anthropogenic climate change. It was traditionally accepted that methane formation is obligatory in methanogens, because all of their respiratory processes converge at the reaction whereby methyl-coenzyme M (methyl-CoM ) is reduced to methane, catalyzed by methyl-CoM reductase (Mcr). During growth of Methanosarcina acetivorans on carbon monoxide (CO) methane is not the primary catabolic end product, but acetate. By rational and random gene deletions, an M. acetivorans strain was isolated that grew acetogenically and produced almost no methane, despite Mcr remaining essential. Alleviating the basis for Mcr essentiality allowed to inactivate Mcr, thereby creating an experimental chassis to investigate alternative modes of energy metabolism in a former “methanogen”. One aim of the proposed research is to characterize the use, both methanogenic, acetogenic, or via extracellular respiration, of novel electron donors and acceptors, thereby potentially reassessing the role “methanogens” play in the environment. Another aim is to exploit the dispensability of Mcr by studying in vivo structure/function relations of Mcr homologs. Physiological and biochemical analysis of the of constructed strains and enzymes they produce will be employed to achieve the envisioned goals. The research proposed will be paradigmatic for the catabolic capabilities of Methanosarcina, which are probably much broader than previously appreciated.

• DFG Programme: Research Grants