ID   NIFK_METBA              Reviewed;         456 AA.
AC   P51754;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1996, sequence version 1.
DT   03-AUG-2022, entry version 76.
DE   RecName: Full=Nitrogenase molybdenum-iron protein beta chain;
DE            EC=1.18.6.1;
DE   AltName: Full=Dinitrogenase;
DE   AltName: Full=Nitrogenase component I;
GN   Name=nifK2;
OS   Methanosarcina barkeri.
OC   Archaea; Euryarchaeota; Stenosarchaea group; Methanomicrobia;
OC   Methanosarcinales; Methanosarcinaceae; Methanosarcina.
OX   NCBI_TaxID=2208;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 43241 / DSM 1538 / 227;
RX   PubMed=8550408; DOI=10.1128/jb.178.1.143-148.1996;
RA   Chien Y.-T., Zinder S.H.;
RT   "Cloning, functional organization, transcript studies, and phylogenetic
RT   analysis of the complete nitrogenase structural genes (nifHDK2) and
RT   associated genes in the archaeon Methanosarcina barkeri 227.";
RL   J. Bacteriol. 178:143-148(1996).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-45.
RC   STRAIN=ATCC 43241 / DSM 1538 / 227;
RX   PubMed=7961410; DOI=10.1128/jb.176.21.6590-6598.1994;
RA   Chien Y.-T., Zinder S.H.;
RT   "Cloning, DNA sequencing, and characterization of a nifD-homologous gene
RT   from the archaeon Methanosarcina barkeri 227 which resembles nifD1 from the
RT   eubacterium Clostridium pasteurianum.";
RL   J. Bacteriol. 176:6590-6598(1994).
CC   -!- FUNCTION: This molybdenum-iron protein is part of the nitrogenase
CC       complex that catalyzes the key enzymatic reactions in nitrogen
CC       fixation.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=16 ATP + 16 H2O + N2 + 8 reduced [2Fe-2S]-[ferredoxin] = 16
CC         ADP + 6 H(+) + H2 + 2 NH4(+) + 8 oxidized [2Fe-2S]-[ferredoxin] + 16
CC         phosphate; Xref=Rhea:RHEA:21448, Rhea:RHEA-COMP:10000, Rhea:RHEA-
CC         COMP:10001, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:17997,
CC         ChEBI:CHEBI:18276, ChEBI:CHEBI:28938, ChEBI:CHEBI:30616,
CC         ChEBI:CHEBI:33737, ChEBI:CHEBI:33738, ChEBI:CHEBI:43474,
CC         ChEBI:CHEBI:456216; EC=1.18.6.1;
CC   -!- COFACTOR:
CC       Name=[8Fe-7S] cluster; Xref=ChEBI:CHEBI:21143; Evidence={ECO:0000250};
CC       Note=Binds 1 [8Fe-7S] cluster per heterodimer. {ECO:0000250};
CC   -!- SUBUNIT: Tetramer of two alpha and two beta chains. Forms complex with
CC       the iron protein (nitrogenase component 2).
CC   -!- SIMILARITY: Belongs to the NifD/NifK/NifE/NifN family. {ECO:0000305}.
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DR   EMBL; U32665; AAA96014.1; -; Genomic_DNA.
DR   EMBL; U11291; AAA65881.1; -; Genomic_DNA.
DR   AlphaFoldDB; P51754; -.
DR   SMR; P51754; -.
DR   PRIDE; P51754; -.
DR   GO; GO:0016612; C:molybdenum-iron nitrogenase complex; IEA:InterPro.
DR   GO; GO:0005524; F:ATP binding; IEA:UniProtKB-KW.
DR   GO; GO:0018697; F:carbonyl sulfide nitrogenase activity; IEA:UniProtKB-EC.
DR   GO; GO:0051536; F:iron-sulfur cluster binding; IEA:UniProtKB-KW.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0016163; F:nitrogenase activity; IEA:UniProtKB-EC.
DR   GO; GO:0009399; P:nitrogen fixation; IEA:UniProtKB-KW.
DR   InterPro; IPR000510; Nase/OxRdtase_comp1.
DR   InterPro; IPR000318; Nase_comp1_CS.
DR   InterPro; IPR005976; Nase_Mo-Fe_CF_bsu.
DR   Pfam; PF00148; Oxidored_nitro; 1.
DR   TIGRFAMs; TIGR01286; nifK; 1.
DR   PROSITE; PS00699; NITROGENASE_1_1; 1.
PE   3: Inferred from homology;
KW   ATP-binding; Iron; Iron-sulfur; Metal-binding; Nitrogen fixation;
KW   Nucleotide-binding; Oxidoreductase.
FT   CHAIN           1..456
FT                   /note="Nitrogenase molybdenum-iron protein beta chain"
FT                   /id="PRO_0000153102"
FT   BINDING         23
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with alpha chain"
FT                   /evidence="ECO:0000250"
FT   BINDING         48
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with alpha chain"
FT                   /evidence="ECO:0000250"
FT   BINDING         106
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with alpha chain"
FT                   /evidence="ECO:0000250"
FT   BINDING         141
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with alpha chain"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   456 AA;  49347 MW;  440A118E552549DF CRC64;
     MLDYTPCEEV TREAVTINPA KTCQPIGAVY AALGVHNCMP HSHGSQGCLS YLRMCLSRHY
     REAALATTSS FSEGTAVFGV SANLKEALVN LTTIYKPEVI AIHTTCVAET IGDDVGVILE
     DVEAEELIDP SIKICAASTP SYVGSHITGY DNMVKSFVTT FTKKSKPNGK LNIIPGFVEP
     GDIREIKRIL SIMEISSIVF PDTTDVFGAP LTGEPGMYPK GGTPIGDIED SANSVGTIAL
     CRMAGGSAAK ILEGRYKVPA KIGPTPIGIR NTDRFVMNAA KLANVAIPPE LEDERGRLVD
     MMTDAHPHYH GKKVAIYGDP DILTGLTSLV MEMGMEPVVV LTGTKSSEFE KEVEGLIGPE
     HPEADVISGG DMFTLHQIIK RKPVDLLIGN TYGKFISRAE DVPLVRVGFP IMDRANLHYF
     PIMGYAGAAR LVERIANTLL DRKDRDAPDW LLETIQ