This enzyme catalyses the final step in methanogenesis, the biological production of methane. This important anaerobic process is carried out only by methanogenic archaea. The enzyme can also function in reverse, for anaerobic oxidation of methane.The enzyme requires the hydroporphinoid nickel complex coenzyme F430. Highly specific for coenzyme B with a heptanoyl chain; ethyl CoM and difluoromethyl CoM are poor substrates. The sulfide sulfur can be replaced by selenium but not by oxygen.
The taxonomic range for the selected organisms is: Methanosarcina barkeri The expected taxonomic range for this enzyme is: Archaea, Eukaryota, Bacteria
Synonyms
methyl-coenzyme m reductase, methyl coenzyme m reductase, methyl-com reductase, methyl coenzyme-m reductase, mcr ii, mcr i, mcrox1, methyl coenzyme m reductase a, methyl-coenzyme-m reductase, methyl-coenzyme m reductase a, more
in the active site region of both isozymes, modified amino acids occur determined by mass spectrometry: thioglycine alpha445, forming a thioxo peptide/thioamide bond with tyrosine alpha446, S-methylcysteine alpha452, 1-N-methylhistidine alpha257 and 5-(S)-methylarginine alpha271
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SYSTEMATIC NAME
IUBMB Comments
methyl-CoM:CoB S-(2-sulfoethyl)thiotransferase
This enzyme catalyses the final step in methanogenesis, the biological production of methane. This important anaerobic process is carried out only by methanogenic archaea. The enzyme can also function in reverse, for anaerobic oxidation of methane.The enzyme requires the hydroporphinoid nickel complex coenzyme F430. Highly specific for coenzyme B with a heptanoyl chain; ethyl CoM and difluoromethyl CoM are poor substrates. The sulfide sulfur can be replaced by selenium but not by oxygen.
MCR contains a thioxo peptide bond and methylated amino acids in the active site region, the number of methylated amino acids varies between species, overview
the enzyme molecule contains two mol of the nickel porphinoid factor 430 non-covalently bound. The nickel center of F430 is coordinated by the coenzyme M sulfhydryl group from one side and by the oxygen atom of a glutamine side-chain from the other
nickel enzyme. The nickel center of F430 is coordinated by the coenzyme M sulfhydryl group from one side and by the oxygen atom of a glutamine side-chain from the other
methyl-coenzyme M reductase is a key enzyme in methanogenic and methanotrophic Archaea. Methyl-coenzyme M reductase (MCR) is a unique enzyme found exclusively in anaerobic archaea, where it catalyzes the reversible conversion of methyl-coenzyme M (CoM, 2-methylmercaptoethane-sulfonate) and coenzyme B (CoB, 7-thioheptanoylthreoninephosphate) to methane and a CoB-CoM heterodisulfide. The activity plays a critical role in the global carbon cycle
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
hanging drop method, comparison of crystal structures of methyl-coenzyme M reductase from Methanosarcina barkeri (growth temperature optimum, 37°C), Methanopyrus kandleri (growth temperature optimum, 98°C) and Methanobacterium thermoautotrophicum (growth temperature optimum, 65°C)
the crystal structures of methyl-coenzyme M reductase from Methanosarcina barkeri and Methanopyrus kandleri are determined and compared with the known structure of MCR from Methanobacterium thermoautotrophicum. The active sites of enzyme from Methanosarcina barkeri and Methanopyrus kandleri are almost identical to that of Methanobacterium thermoautotrophicum and predominantly occupied by coenzyme M and coenzyme B. The electron density at 1.6 A resolution of the Methanosarcina barkeri enzyme reveals that four of the modified amino acid residues of enzyme from Methanopyrus thermoautotrophicum, namely a thiopeptide, an S-methylcysteine, a 1-N-methylhistidine and a 5-methylarginine are also present. Crystals of the enzyme from Methanosarcina barkeri are grown using a reservoir condition with PEG 5000 monomethylether as precipitant and glycerol as cryoprotectant
Grabarse, W.; Mahlert, F.; Shima, S.; Thauer, R.K.; Ermler, U.
Comparison of three methyl-coenzyme M reductases from phylogenetically distant organisms: unusual amino acid modification, conservation and adaptation
J. Mol. Biol.
303
329-344
2000
Methanopyrus kandleri (Q49605 and Q49601 and Q49604), Methanopyrus kandleri, Methanopyrus kandleri DSM 6324 (Q49605 and Q49601 and Q49604), Methanosarcina barkeri (P07962 and P07955 and P07964), Methanosarcina barkeri, Methanosarcina barkeri DSM 804 (P07962 and P07955 and P07964)
Scheller, S.; Goenrich, M.; Thauer, R.K.; Jaun, B.
Methyl-coenzyme M reductase from methanogenic archaea: isotope effects on label exchange and ethane formation with the homologous substrate ethyl-coenzyme M
Post-translational thioamidation of methyl-coenzyme M reductase, a key enzyme in methanogenic and methanotrophic Archaea
eLife
6
e29218
2017
Methanosarcina barkeri (P07962 and P07955 and P07964), Methanosarcina acetivorans (Q8THH1 AND Q8THG7 AND Q8THH0), Methanosarcina acetivorans, Methanosarcina acetivorans ATCC 35395 (Q8THH1 AND Q8THG7 AND Q8THH0), Methanosarcina barkeri Fusaro (P07962 and P07955 and P07964), Methanosarcina acetivorans DSM 2834 (Q8THH1 AND Q8THG7 AND Q8THH0), Methanosarcina acetivorans JCM 12185 (Q8THH1 AND Q8THG7 AND Q8THH0), Methanosarcina barkeri DSM 804 (P07962 and P07955 and P07964)