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: Methanopyrus kandleri 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
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
methyl-CoM + CoB = CoM-S-S-CoB + methane
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, 2-(S)-methylglutamine alpha400, 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
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
ammonium sulfate precipitation, crystals of the inactive enzyme are obtained with PEG 550 monomethyl ether as precipitant. Diffraction data to 2.7 A resolution are collected from one crystal of methyl-coenzyme M reductase from Methanopyrus kandleri with a completeness of 63%. Due to the low completeness of the data, refinement of the structure is only possible constraining the 2-fold non-crystallographic symmetry of the methyl-coenzyme M reductase molecule. 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. Crystals of the inactive enzyme from Methanopyrus kandleri are obtained by hanging drop method with PEG 550 monomethylether as precipitant
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)