Structure of a methyl-coenzyme M reductase from Black Sea mats that oxidize methane anaerobically

• Published in: Nature (London) Vol. 481; no. 7379; pp. 98 - 101
• Main Authors: Shima, Seigo, Krueger, Martin, Weinert, Tobias, Demmer, Ulrike, Kahnt, Jörg, Thauer, Rudolf K, Ermler, Ulrich
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 05.01.2012
• Subjects: Amino acids; Anaerobiosis; Archaea - enzymology; Archaea - isolation & purification; Archaea - metabolism; Biocatalysis; Black Sea; Catalytic Domain; Chemical structure; Coenzymes - chemistry; Coenzymes - metabolism; Crystal lattices; Crystal structure; Crystallization; Crystallography, X-Ray; Crystals; Cysteine - metabolism; Environmental aspects; Enzymes; Expeditions; Methane; Methane - metabolism; Methods; Methyl groups; Microbial mats; Microbiology; Microorganisms; Models, Molecular; Oxidation-Reduction; Oxidoreductases - chemistry; Oxidoreductases - metabolism; Properties; Prostheses; Protein Conformation; Proteins; Seawater - microbiology; Ships; Sulfate reduction; Sulfates; Sulfates - metabolism; Black Sea; Germany
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature10663

The anaerobic oxidation of methane (AOM) with sulphate, an area currently generating great interest in microbiology, is accomplished by consortia of methanotrophic archaea (ANME) and sulphate-reducing bacteria. The enzyme activating methane in methanotrophic archaea has tentatively been identified as a homologue of methyl-coenzyme M reductase (MCR) that catalyses the methane-forming step in methanogenic archaea. Here we report an X-ray structure of the 280 kDa heterohexameric ANME-1 MCR complex. It was crystallized uniquely from a protein ensemble purified from consortia of microorganisms collected with a submersible from a Black Sea mat catalysing AOM with sulphate. Crystals grown from the heterogeneous sample diffract to 2.1 Å resolution and consist of a single ANME-1 MCR population, demonstrating the strong selective power of crystallization. The structure revealed ANME-1 MCR in complex with coenzyme M and coenzyme B, indicating the same substrates for MCR from methanotrophic and methanogenic archaea. Differences between the highly similar structures of ANME-1 MCR and methanogenic MCR include a F(430) modification, a cysteine-rich patch and an altered post-translational amino acid modification pattern, which may tune the enzymes for their functions in different biological contexts.