The vast majority of methane, a potent greenhouse gas, released in the atmosphere is produced by a group of microorganisms called methanogens. Close relatives of methanogens, called anaerobic methane oxidizing archaea (referred to as ANME henceforth), consume methane through a reversal of the canonical methanogenesis pathway. As such, ANME consume a significant fraction of methane produced by methanogens, especially in marine environments. Unlike methanogens, ANME have been recalcitrant to routine laboratory cultivation techniques so far. Therefore, biochemical characterization of anaerobic methane oxidation in these keystone microorganisms has proven to be extremely challenging. To overcome this challenge, my research group is developing a closely related methanogen, Methanosarcina acetivorans, as a genetic chassis to study genes from ANME with the ultimate goal to build a synthetic ANME de novo. Metagenome-assembled genomes of ANME are enriched in large multi-heme c-type cytochromes (referred to as MHCs henceforth) that are notably absent in closely related methanogens like M. acetivorans. These MHCs are hypothesized to facilitate anaerobic methane oxidation by efficient extracellular transfer of electrons thus generated. Ultimately, these MHCs transfer the electrons to a partner bacterium or to redox-active Fe, Mn containing minerals. In this talk, I will discuss the findings from two recent studies in my group to: a) identify and characterize the c-type cytochrome maturation machinery in methanogenic archaea and b) conduct heterologous expression and biochemical characterization of ANME MHCs.