Spectroscopic and computational characterization of the nickel-containing F430 cofactor of methyl-coenzyme M reductase

(R)-Sulfolactate dehydrogenase (EC 1.1.1.337), termed ComC, is a member of an NADH/NADPH-dependent oxidoreductase family of enzymes that catalyze the interconversion of 2-hydroxyacids into their corresponding 2-oxoacids. The ComC reaction is reversible and in the biosynthetic direction causes the conversion of (R)-sulfolactate to sulfopyruvate in the production of coenzyme M (2-mercaptoethanesulfonic acid). Coenzyme M is an essential cofactor required for the production of methane by the methyl-coenzyme M reductase complex. ComC catalyzes the third step in the first established biosynthetic pathway of coenzyme M and is also involved in methanopterin biosynthesis. In this study, ComC fromMethanobrevibacter milleraeSM9 was cloned and expressed inEscherichia coliand biochemically characterized. Sulfopyruvate was the preferred substrate using the reduction reaction, with 31% activity seen for oxaloacetate and 0.2% seen forα-ketoglutarate. Optimal activity was observed at pH 6.5. The apparentKMfor coenzyme (NADH) was 55.1 μM, and for sulfopyruvate, it was 196 μM (for sulfopyruvate theVmaxwas 93.9 μmol min−1 mg−1andkcatwas 62.8 s−1). The critical role of ComC in two separate cofactor pathways makes this enzyme a potential means of developing methanogen-specific inhibitors for controlling ruminant methane emissions which are increasingly being recognized as contributing to climate change.

Download Full-text

Post-translational thioamidation of methyl-coenzyme M reductase, a key enzyme in methanogenic and methanotrophic Archaea

10.1101/121111 ◽

2017 ◽

Author(s):

Dipti D. Nayak ◽

Nilkamal Mahanta ◽

Douglas A. Mitchell ◽

William W. Metcalf

Keyword(s):

Strictly Anaerobic ◽

Methanosarcina Acetivorans ◽

Coenzyme M ◽

Α Subunit ◽

Post Translational Modifications ◽

Physiological Characterization ◽

Key Enzyme ◽

Catalytic Role ◽

Methyl Coenzyme M Reductase

AbstractThe enzyme methyl-coenzyme M reductase (MCR), found in strictly anaerobic methanogenic and methanotrophic archaea, catalyzes a reversible reaction involved in the production and consumption of the potent greenhouse gas methane. The α subunit of this enzyme (McrA) contains several unusual post-translational modifications, including an exceptionally rare thioamidation of glycine. Based on the presumed function of homologous genes involved in the biosynthesis of thioamide-containing natural products, we hypothesized that the archaealtfuAandycaOgenes would be responsible for post-translational installation of thioglycine into McrA. Mass spectrometric characterization of McrA in a ΔycaO-tfuAmutant of the methanogenic archaeonMethanosarcina acetivoransrevealed the presence of glycine, rather than thioglycine, supporting this hypothesis. Physiological characterization of this mutant suggested a new role for the thioglycine modification in enhancing protein stability, as opposed to playing a direct catalytic role. The universal conservation of this modification suggests that MCR arose in a thermophilic ancestor.

Download Full-text

Cloning and Characterization of the Methyl Coenzyme M Reductase Genes from Methanobacterium thermoautotrophicum :

Journal of Bacteriology ◽

10.1128/jb.170.8.3792a.1988 ◽

1988 ◽

Vol 170 (8) ◽

pp. 3792.1-3792

Keyword(s):

Methanobacterium Thermoautotrophicum ◽

Coenzyme M ◽

Methyl Coenzyme M Reductase

Download Full-text

Cryoreduction of Methyl-Coenzyme M Reductase: EPR Characterization of Forms, MCRox1and MCRred1

Journal of the American Chemical Society ◽

10.1021/ja010428d ◽

2001 ◽

Vol 123 (25) ◽

pp. 5853-5860 ◽

Cited By ~ 32

Author(s):

Joshua Telser ◽

Roman Davydov ◽

Yih-Chern Horng ◽

Stephen W. Ragsdale ◽

Brian M. Hoffman

Keyword(s):

Coenzyme M ◽

Methyl Coenzyme M Reductase

Download Full-text

Post-translational thioamidation of methyl-coenzyme M reductase, a key enzyme in methanogenic and methanotrophic Archaea

eLife ◽

10.7554/elife.29218 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 41

Author(s):

Dipti D Nayak ◽

Nilkamal Mahanta ◽

Douglas A Mitchell ◽

William W Metcalf

Keyword(s):

Elevated Temperatures ◽

Protein Secondary Structure ◽

Phenotypic Characterization ◽

Strictly Anaerobic ◽

Methanosarcina Acetivorans ◽

Coenzyme M ◽

Α Subunit ◽

Key Enzyme ◽

Methyl Coenzyme M Reductase

Methyl-coenzyme M reductase (MCR), found in strictly anaerobic methanogenic and methanotrophic archaea, catalyzes the reversible production and consumption of the potent greenhouse gas methane. The α subunit of MCR (McrA) contains several unusual post-translational modifications, including a rare thioamidation of glycine. Based on the presumed function of homologous genes involved in the biosynthesis of thioviridamide, a thioamide-containing natural product, we hypothesized that the archaeal tfuA and ycaO genes would be responsible for post-translational installation of thioglycine into McrA. Mass spectrometric characterization of McrA from the methanogenic archaeon Methanosarcina acetivorans lacking tfuA and/or ycaO revealed the presence of glycine, rather than thioglycine, supporting this hypothesis. Phenotypic characterization of the ∆ycaO-tfuA mutant revealed a severe growth rate defect on substrates with low free energy yields and at elevated temperatures (39°C - 45°C). Our analyses support a role for thioglycine in stabilizing the protein secondary structure near the active site.

Download Full-text