title: Methanotrophic archaea possessing diverging methane-oxidizing and electron-transporting pathways.
abstract: Anaerobic oxidation of methane (AOM) is a crucial process limiting the flux of methane from marine environments to the atmosphere. The process is thought to be mediated by three groups of uncultivated methane-oxidizing archaea (ANME-1, 2 and 3). Although the responsible microbes have been intensively studied for more than a decade, central mechanistic details remain unresolved. On the basis of an integrated analysis of both environmental metatranscriptome and single-aggregate genome of a highly active AOM enrichment dominated by ANME-2a, we provide evidence for a complete and functioning AOM pathway in ANME-2a. All genes required for performing the seven steps of methanogenesis from CO2 were found present and actively expressed. Meanwhile, genes for energy conservation and electron transportation including those encoding F420H2 dehydrogenase (Fpo), the cytoplasmic and membrane-associated Coenzyme B-Coenzyme M heterodisulfide (CoB-S-SCoM) reductase (HdrABC, HdrDE), cytochrome C and the Rhodobacter nitrogen fixation (Rnf) complex were identified and expressed, whereas genes encoding for hydrogenases were absent. Thus, ANME-2a is likely performing AOM through a complete reversal of methanogenesis from CO2 reduction without involvement of canonical hydrogenase. ANME-2a is demonstrated to possess versatile electron transfer pathways that would provide the organism with more flexibility in substrate utilization and capacity for rapid adjustment to fluctuating environments. This work lays the foundation for understanding the environmental niche differentiation, physiology and evolution of different ANME subgroups.
authors: 1] State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China [2] State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China [3] Key Laboratory of Systems Biomedicine (Ministry of Education), School of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors: Feng-Ping
authors: FP
authors: Wang
authors: 1] State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China [2] State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China [3] Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Gent, Belgium.
authors: Yu
authors: Y
authors: Zhang
authors: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors: Ying
authors: Y
authors: Chen
authors: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors: Ying
authors: Y
authors: He
authors: School of Life Sciences, Fu Dan University, Shanghai, People's Republic of China.
authors: Ji
authors: J
authors: Qi
authors: MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany.
authors: Kai-Uwe
authors: KU
authors: Hinrichs
authors: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors: Xin-Xu
authors: XX
authors: Zhang
authors: 1] State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China [2] State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors: Xiang
authors: X
authors: Xiao
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Gent, Belgium.
authors: Nico
authors: N
authors: Boon
mesh_terms: D000085:Acetates / Q000378:metabolism; D001105:Archaea / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D004583:Electrons; D019848:Gene Expression Regulation, Archaeal; D020745:Genome, Archaeal; D019015:Geologic Sediments / Q000382:microbiology*; D006859:Hydrogen / Q000378:metabolism; D008697:Methane / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases
chemical_list: D000085:Acetates; D006859:Hydrogen; C072742:F420H2 dehydrogenase; D010088:Oxidoreductases; D008697:Methane