5a0y

Publication Abstract from PubMed

All methanogenic and methanotrophic archaea known to date contain methyl-coenzyme M reductase (MCR) that catalyzes the reversible reduction of methyl-coenzyme M to methane. This enzyme contains the nickel porphinoid F430 as a prosthetic group and, highly conserved, a thioglycine and four methylated amino acid residues near the active site. We describe herein the presence of a novel post-translationally modified amino acid, didehydroaspartate, adjacent to the thioglycine as revealed by mass spectrometry and high-resolution X-ray crystallography. Upon chemical reduction, the didehydroaspartate residue was converted into aspartate. Didehydroaspartate was found in MCR I and II from Methanothermobacter marburgensis and in MCR of phylogenetically distantly related Methanosarcina barkeri but not in MCR I and II of Methanothermobacter wolfeii, which indicates that didehydroaspartate is dispensable but might have a role in fine-tuning the active site to increase the catalytic efficiency.

Didehydroaspartate Modification in Methyl-Coenzyme M Reductase Catalyzing Methane Formation.,Wagner T, Kahnt J, Ermler U, Shima S Angew Chem Int Ed Engl. 2016 Jul 28. doi: 10.1002/anie.201603882. PMID:27467699^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.