The Na(+)-translocating methyltransferase complex from methanogenic archaea.

G Gottschalk, R K Thauer

Journal: Biochimica et biophysica acta 2001;1505(1):28-36

PMID: 11248186

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Abstract

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.

Address: Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Germany.

DOI: 10.1016/s0005-2728(00)00274-7

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MeSH Terms: Amino Acid Sequence, Archaeal Proteins, Bacterial Proteins, Cations, Monovalent, Cell Membrane, Corrinoids, Euryarchaeota, Methane, Methyltransferases, Models, Molecular, Molecular Sequence Data, Molecular Structure, Multienzyme Complexes, Porphyrins, Protein Conformation, Sodium