ID   MCRA_METVO              Reviewed;         555 AA.
AC   P11559;
DT   01-OCT-1989, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1989, sequence version 1.
DT   04-NOV-2026, entry version 106.
DE   RecName: Full=Methyl-coenzyme M reductase subunit alpha;
DE            EC=2.8.4.1 {ECO:0000250|UniProtKB:P11558};
DE   AltName: Full=Coenzyme-B sulfoethylthiotransferase alpha;
GN   Name=mcrA;
OS   Methanococcus voltae.
OC   Archaea; Methanobacteriati; Methanobacteriota; Methanomada group;
OC   Methanococci; Methanococcales; Methanococcaceae; Methanococcus.
OX   NCBI_TaxID=2188;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 33273 / DSM 1537 / NBRC 100457 / OCM 70 / PS;
RX   PubMed=3185509; DOI=10.1007/bf00339610;
RA   Klein A., Allmansberger R., Bokranz M., Knaub S., Mueller B., Muth E.;
RT   "Comparative analysis of genes encoding methyl coenzyme M reductase in
RT   methanogenic bacteria.";
RL   Mol. Gen. Genet. 213:409-420(1988).
CC   -!- FUNCTION: Component of the methyl-coenzyme M reductase (MCR) I that
CC       catalyzes the reductive cleavage of methyl-coenzyme M (CoM-S-CH3 or 2-
CC       (methylthio)ethanesulfonate) using coenzyme B (CoB or 7-
CC       mercaptoheptanoylthreonine phosphate) as reductant which results in the
CC       production of methane and the mixed heterodisulfide of CoB and CoM
CC       (CoM-S-S-CoB). This is the final step in methanogenesis.
CC       {ECO:0000250|UniProtKB:P11558}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=coenzyme B + methyl-coenzyme M = coenzyme M-coenzyme B
CC         heterodisulfide + methane; Xref=Rhea:RHEA:12532, ChEBI:CHEBI:16183,
CC         ChEBI:CHEBI:58286, ChEBI:CHEBI:58411, ChEBI:CHEBI:58596; EC=2.8.4.1;
CC         Evidence={ECO:0000250|UniProtKB:P11558};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:12533;
CC         Evidence={ECO:0000250|UniProtKB:P11558};
CC   -!- COFACTOR:
CC       Name=coenzyme F430; Xref=ChEBI:CHEBI:60540;
CC         Evidence={ECO:0000250|UniProtKB:P11558};
CC       Note=Binds 2 coenzyme F430 non-covalently per MCR complex. Coenzyme
CC       F430 is a yellow nickel porphinoid. Methyl-coenzyme-M reductase is
CC       activated when the enzyme-bound coenzyme F430 is reduced to the Ni(I)
CC       oxidation state. {ECO:0000250|UniProtKB:P11558};
CC   -!- PATHWAY: One-carbon metabolism; methyl-coenzyme M reduction; methane
CC       from methyl-coenzyme M: step 1/1. {ECO:0000250|UniProtKB:P11558}.
CC   -!- SUBUNIT: MCR is a hexamer of two alpha, two beta, and two gamma chains,
CC       forming a dimer of heterotrimers. {ECO:0000250|UniProtKB:P11558}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250|UniProtKB:P11558}.
CC   -!- SIMILARITY: Belongs to the methyl-coenzyme M reductase alpha subunit
CC       family. {ECO:0000305}.
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DR   EMBL; X07793; CAA30633.1; -; Genomic_DNA.
DR   PIR; S03261; S03261.
DR   AlphaFoldDB; P11559; -.
DR   SMR; P11559; -.
DR   OMA; AAMQQCW; -.
DR   UniPathway; UPA00646; UER00699.
DR   GO; GO:0005737; C:cytoplasm; ISS:UniProtKB.
DR   GO; GO:0050524; F:coenzyme-B sulfoethylthiotransferase activity; ISS:UniProtKB.
DR   GO; GO:0015948; P:methanogenesis; IEA:InterPro.
DR   Gene3D; 3.30.70.470; -; 1.
DR   Gene3D; 1.20.840.10; Methyl-coenzyme M reductase, alpha/beta subunit, C-terminal; 1.
DR   Gene3D; 3.90.390.10; Methyl-coenzyme M Reductase, Chain A, domain 1; 1.
DR   InterPro; IPR016212; Me_CoM_Rdtase_asu.
DR   InterPro; IPR008924; Me_CoM_Rdtase_asu/bsu_C.
DR   InterPro; IPR009047; Me_CoM_Rdtase_asu_C.
DR   InterPro; IPR003183; Me_CoM_Rdtase_asu_N.
DR   InterPro; IPR015811; Me_CoM_Rdtase_asu_N_sub1.
DR   InterPro; IPR015823; Me_CoM_Rdtase_asu_N_sub2.
DR   InterPro; IPR009024; Me_CoM_Rdtase_Fd-like_fold.
DR   NCBIfam; TIGR03256; met_CoM_red_alp; 1.
DR   Pfam; PF02249; MCR_alpha; 1.
DR   Pfam; PF02745; MCR_alpha_N; 1.
DR   PIRSF; PIRSF000262; MCR_alpha; 1.
DR   SUPFAM; SSF48081; Methyl-coenzyme M reductase alpha and beta chain C-terminal domain; 1.
DR   SUPFAM; SSF55088; Methyl-coenzyme M reductase subunits; 1.
PE   3: Inferred from homology;
KW   Cytoplasm; Metal-binding; Methanogenesis; Methylation; Nickel; Transferase.
FT   CHAIN           1..555
FT                   /note="Methyl-coenzyme M reductase subunit alpha"
FT                   /id="PRO_0000147461"
FT   BINDING         152
FT                   /ligand="coenzyme F430"
FT                   /ligand_id="ChEBI:CHEBI:60540"
FT                   /ligand_part="Ni"
FT                   /ligand_part_id="ChEBI:CHEBI:28112"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000250|UniProtKB:P11558"
FT   BINDING         230
FT                   /ligand="coenzyme B"
FT                   /ligand_id="ChEBI:CHEBI:58596"
FT                   /ligand_note="ligand shared between two alpha subunits"
FT                   /note="in chain A"
FT                   /evidence="ECO:0000250|UniProtKB:P11558"
FT   BINDING         261..262
FT                   /ligand="coenzyme B"
FT                   /ligand_id="ChEBI:CHEBI:58596"
FT                   /ligand_note="ligand shared between two alpha subunits"
FT                   /note="in chain A"
FT                   /evidence="ECO:0000250|UniProtKB:P11558"
FT   BINDING         275
FT                   /ligand="coenzyme B"
FT                   /ligand_id="ChEBI:CHEBI:58596"
FT                   /ligand_note="ligand shared between two alpha subunits"
FT                   /note="in chain B"
FT                   /evidence="ECO:0000250|UniProtKB:P11558"
FT   BINDING         337
FT                   /ligand="coenzyme M"
FT                   /ligand_id="ChEBI:CHEBI:58319"
FT                   /evidence="ECO:0000250|UniProtKB:P11558"
FT   BINDING         448
FT                   /ligand="coenzyme M"
FT                   /ligand_id="ChEBI:CHEBI:58319"
FT                   /evidence="ECO:0000250|UniProtKB:P11558"
SQ   SEQUENCE   555 AA;  61227 MW;  DCBCE5DC91EA69D5 CRC64;
     MEAEKRLFLK ALKEKFEEDP KEKFTKFYTY GGWQQSARKQ EFVSENEKIV AEKRGGIPMY
     NPDIGVPLGQ RKLMPYKISN TDTYVEGDDL HFMNNAAIQQ LWDDIRRTVI VGMDTAHMVL
     EKRLGVEVTP ETINEYMHTI NHSLPGGAAV VQEHMVEVHP SLAWDCYAKI FTGDDELADE
     LDDRFVIDIN KLFPEEQAEA SKAAIGKKTY QVSRVPSLVG RVCDGGTISR WSAMQIGMSF
     ITAYKLCAGE AAIADFSYAA KHADVIQMGN ALLGRRARGP NELGGVRFGI LSDVVQTTRV
     SDDPVEQSLE VVATGAALYD QIWLGSYMSG GVGFTQYATA SYTDDILDDF SYYGYEYVEK
     KYGRCGTKAT MDVVEDIASE VTLYALEQYD EYPALLEDHF GGSQRAAVAA AAAGISVCMA
     TGNSNAGVNG WYLSQILHKE YHSRLGFYGY DLQDQCGASN SLAIRNDEAS PLELRGPNYP
     NYAMNVGHQG EYAGIAQSAH SARGDAFATN ALIKVAFADP SLVFDFSKPR KEIARGALRE
     FEAAGERDPI LPAKI
//