ID   NIFK_AZOBR              Reviewed;         521 AA.
AC   P25314;
DT   01-MAY-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1992, sequence version 1.
DT   03-AUG-2022, entry version 81.
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=nifK;
OS   Azospirillum brasilense.
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Rhodospirillales;
OC   Azospirillaceae; Azospirillum.
OX   NCBI_TaxID=192;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=1823284;
RA   Passaglia L.M.P., Nunes C.P., Zaha A., Schrank I.S.;
RT   "The nifHDK operon in the free-living nitrogen-fixing bacteria Azospirillum
RT   brasilense sequentially comprises genes H, D, K, an 353 bp orf and gene
RT   Y.";
RL   Braz. J. Med. Biol. Res. 24:649-675(1991).
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   -!- MISCELLANEOUS: Ala-194 is present instead of the usual Ser that would
CC       serve as a ligand for the 8Fe-7S cluster in the oxidized state.
CC   -!- SIMILARITY: Belongs to the NifD/NifK/NifE/NifN family. {ECO:0000305}.
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DR   EMBL; M64344; AAB02344.1; -; Genomic_DNA.
DR   PIR; S27475; S27475.
DR   AlphaFoldDB; P25314; -.
DR   SMR; P25314; -.
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   InterPro; IPR024564; Nase_Mo-Fe_CF_bsu_N.
DR   Pfam; PF11844; DUF3364; 1.
DR   Pfam; PF00148; Oxidored_nitro; 1.
DR   TIGRFAMs; TIGR01286; nifK; 1.
DR   PROSITE; PS00699; NITROGENASE_1_1; 1.
DR   PROSITE; PS00090; NITROGENASE_1_2; 1.
PE   3: Inferred from homology;
KW   ATP-binding; Iron; Iron-sulfur; Metal-binding; Nitrogen fixation;
KW   Nucleotide-binding; Oxidoreductase.
FT   CHAIN           1..521
FT                   /note="Nitrogenase molybdenum-iron protein beta chain"
FT                   /id="PRO_0000153087"
FT   BINDING         77
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         102
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         159
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   521 AA;  58216 MW;  4056110ED573DBA4 CRC64;
     MSMSHPVSQS ADKVIDHFTL FRQPEYKELF ERKKTEFEYG PTPTKEVARV SAWTKTEEYK
     EKNLPVEAVV INPTKACQPI GAMLAAQGFE GTLPFVHGSQ GCVSYYRTHL TRHFKEPNSA
     VSSSMTEDAA VFGGLNNMID GLQRYALYKP KMIAVLTTCM AEVIGDDLSG FINNAKNKES
     VPADFPVPFA HTPAFVGSHI VGYDNMIKGV LTHFWGTSEN FDTPKNETIN LIPGFDGFAV
     GNNRELKRIA GLFGIQMTIL SDVSDNFDTP ADGEYRMYDG GTPLEATKEA VHAKATISMQ
     EYCTPQSLQF IKREGPAGRQ AYNYPMGVTG TDELLMKLAE LSGKPSRGVK LERGRLVDAI
     ADSHTHLHGK RFAVYGDPDF CLGMSKFLME LGAEPVHILS TSGSKKWEKQ VQKVLDACRS
     ASSGKAYGAK DLWHLRSLVF TDKVDYIIGN SYGKYLERDT KIPLIRLTYP IFDRHHHHRY
     PTWGYQGALN VLVRILDRIF EDMDANTNIV GETDYSFDLV R