title: Long-Lasting Gene Conversion Shapes the Convergent Evolution of the Critical Methanogenesis Genes.
abstract: Methanogenesis and its key small-molecule methyltransferase Mtr complex are poorly understood despite their pivotal role in Earth's global carbon cycle. Mtr complex is encoded by a conserved mtrEDCBAFGH operon in most methanogens. Here we report that two discrete lineages, Methanococcales and Methanomicrobiales, have a noncanonical mtr operon carrying two copies of mtrA resulting from an ancient duplication. Compared to mtrA-1, mtrA-2 acquires a distinct transmembrane domain through domain shuffling and gene fusion. However, the nontransmembrane domains (MtrA domain) of mtrA-1 and mtrA-2 are homogenized by gene conversion events lasting throughout the long history of these extant methanogens (over 2410 million years). Furthermore, we identified a possible recruitment of ancient nonmethanogenic methyltransferase genes to establish the methanogenesis pathway. These results not only provide novel evolutionary insight into the methanogenesis pathway and methyltransferase superfamily but also suggest an unanticipated long-lasting effect of gene conversion on gene evolution in a convergent pattern.
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada wangsishuo@yeah.net lou@cau.edu.cn.
authors.forename: Sishuo
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada Department of Renewable Resources, University of Alberta, Edmonton, T6G 2H1, Canada.
authors.forename: Youhua
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Qinhong
authors.initials: Q
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China wangsishuo@yeah.net lou@cau.edu.cn.
authors.forename: Huiqiang
authors.identifier: http://orcid.org/0000-0003-4465-6186
authors.initials: H
authors.lastname: Lou
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005785:Gene Conversion; D019766:Genes, Archaeal; D017015:Methanococcales / Q000235:genetics*; D017018:Methanomicrobiales / Q000235:genetics*; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data
chemical_list: D019843:Archaeal Proteins; D008780:Methyltransferases
keywords: concerted evolution; gene conversion; gene fusion; methanogenesis; methyltransferase