The Na(+)-translocating methyltransferase complex from methanogenic archaea.
Methanogenic archaea are dependent on sodium ions for methane formation. A sodium ion-dependent step has been shown to be methyl transfer from N(5)-methyltetrahydromethanopterin to coenzyme M. This exergonic reaction (DeltaG degrees '=-30 kJ/mol) is catalyzed by a Na(+)-translocating membrane-associated multienzyme complex composed of eight different subunits, MtrA-H. Subunit MtrA harbors a cob(I)amide prosthetic group which is methylated and demethylated in the catalytic cycle, demethylation being sodium ion-dependent. Based on the finding that in the cob(II)amide oxidation state the corrinoid is bound in a base-off/His-on configuration it is proposed that methyl transfer from MtrA to coenzyme M is associated with a conformational change of the protein and that this change drives the electrogenic translocation of the sodium ions.
Gottschalk
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Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Germany.
Thauer
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RK
D000595:Amino Acid Sequence; D019843:Archaeal Proteins; D001426:Bacterial Proteins / Q000378:metabolism*; D002414:Cations, Monovalent; D002462:Cell Membrane / Q000201:enzymology; D045728:Corrinoids; D019605:Euryarchaeota / Q000201:enzymology*; D008697:Methane / Q000378:metabolism; D008780:Methyltransferases / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011166:Porphyrins / Q000737:chemistry; D011487:Protein Conformation; D012964:Sodium / Q000378:metabolism*
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D002414:Cations, Monovalent; D045728:Corrinoids; D009097:Multienzyme Complexes; D011166:Porphyrins; D012964:Sodium; D008780:Methyltransferases; C023894:methylcobalamin-coenzyme M methyltransferase; C048755:tetrahydromethanopterin S-methyltransferase; D008697:Methane