Methylamine-specific methyltransferase paralogs in Methanosarcina are functionally distinct despite frequent gene conversion

Dipti D. Nayak, William W. Metcalf

Research output: Contribution to journalArticlepeer-review


Sequenced archaeal genomes are mostly smaller and more streamlined than typical bacterial genomes; however, members of the Methanosarcina genus within the Euryarchaeaota are a significant exception, with M. acetivorans being the largest archaeal genome (5.8 Mbp) sequenced thus far. This finding is partially explained by extensive gene duplication within Methanosarcina spp. Significantly, the evolutionary pressures leading to gene duplication and subsequent genome expansion have not been well investigated, especially with respect to biological methane production (methanogenesis), which is the key biological trait of these environmentally important organisms. In this study, we address this question by specifically probing the functional evolution of two methylamine-specific methyltransferase paralogs in members of the Methanosarcina genus. Using the genetically tractable strain, M. acetivorans, we first show that the two paralogs have distinct cellular functions: one being required for methanogenesis from methylamine, the other for use of methylamine as a nitrogen source. Subsequently, through comparative sequence analyses, we show that functional divergence of paralogs is primarily mediated by divergent evolution of the 5′ regulatory region, despite frequent gene conversion within the coding sequence. This unique evolutionary paradigm for functional divergence of genes post-duplication underscores a divergent role for an enzyme singularly associated with methanogenic metabolism in other aspects of cell physiology.

Original languageEnglish (US)
Pages (from-to)2173-2182
Number of pages10
JournalISME Journal
Issue number9
StatePublished - Sep 1 2019

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics


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