ID   NIFH_ANASL              Reviewed;         294 AA.
AC   P33178;
DT   01-OCT-1993, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1993, sequence version 1.
DT   02-SEP-2026, entry version 112.
DE   RecName: Full=Nitrogenase iron protein;
DE            EC=1.18.6.1;
DE   AltName: Full=Nitrogenase Fe protein;
DE   AltName: Full=Nitrogenase component II;
DE   AltName: Full=Nitrogenase reductase;
GN   Name=nifH;
OS   Anabaena sp. (strain L31).
OC   Bacteria; Bacillati; Cyanobacteriota; Cyanophyceae; Nostocales;
OC   Nostocaceae; Anabaena.
OX   NCBI_TaxID=29412;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=8424961; DOI=10.1016/0167-4781(93)90080-w;
RA   Murphy S.T., Jackman D.M., Mulligan M.E.;
RT   "Cloning and nucleotide sequence of the gene for dinitrogenase reductase
RT   (nifH) from the heterocyst-forming cyanobacterium Anabaena sp. L31.";
RL   Biochim. Biophys. Acta 1171:337-340(1993).
CC   -!- FUNCTION: The key enzymatic reactions in nitrogen fixation are
CC       catalyzed by the nitrogenase complex, which has 2 components: the iron
CC       protein and the molybdenum-iron protein. {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=N2 + 8 reduced [2Fe-2S]-[ferredoxin] + 16 ATP + 16 H2O = H2 +
CC         8 oxidized [2Fe-2S]-[ferredoxin] + 2 NH4(+) + 16 ADP + 16 phosphate +
CC         6 H(+); 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=[4Fe-4S] cluster; Xref=ChEBI:CHEBI:49883; Evidence={ECO:0000250};
CC       Note=Binds 1 [4Fe-4S] cluster per dimer. {ECO:0000250};
CC   -!- SUBUNIT: Homodimer. {ECO:0000250}.
CC   -!- PTM: The reversible ADP-ribosylation of Arg-104 inactivates the
CC       nitrogenase reductase and regulates nitrogenase activity.
CC       {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the NifH/BchL/ChlL family. {ECO:0000305}.
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DR   EMBL; L04499; AAA22014.1; -; Genomic_DNA.
DR   AlphaFoldDB; P33178; -.
DR   SMR; P33178; -.
DR   BioCyc; MetaCyc:MONOMER-16469; -.
DR   GO; GO:0005524; F:ATP binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0016163; F:nitrogenase activity; IEA:UniProtKB-UniRule.
DR   CDD; cd02040; NifH; 1.
DR   FunFam; 3.40.50.300:FF:001379; Nitrogenase iron protein 1; 1.
DR   Gene3D; 3.40.50.300; P-loop containing nucleotide triphosphate hydrolases; 1.
DR   HAMAP; MF_00533; NifH; 1.
DR   InterPro; IPR030655; NifH/chlL_CS.
DR   InterPro; IPR000392; NifH/frxC.
DR   InterPro; IPR005977; Nitrogenase_Fe_NifH.
DR   InterPro; IPR027417; P-loop_NTPase.
DR   NCBIfam; TIGR01287; nifH; 1.
DR   PANTHER; PTHR42864; LIGHT-INDEPENDENT PROTOCHLOROPHYLLIDE REDUCTASE IRON-SULFUR ATP-BINDING PROTEIN; 1.
DR   PANTHER; PTHR42864:SF2; LIGHT-INDEPENDENT PROTOCHLOROPHYLLIDE REDUCTASE IRON-SULFUR ATP-BINDING PROTEIN; 1.
DR   Pfam; PF00142; Fer4_NifH; 1.
DR   PIRSF; PIRSF000363; Nitrogenase_iron; 1.
DR   PRINTS; PR00091; NITROGNASEII.
DR   SUPFAM; SSF52540; P-loop containing nucleoside triphosphate hydrolases; 1.
DR   PROSITE; PS00746; NIFH_FRXC_1; 1.
DR   PROSITE; PS00692; NIFH_FRXC_2; 1.
DR   PROSITE; PS51026; NIFH_FRXC_3; 1.
PE   3: Inferred from homology;
KW   4Fe-4S; ADP-ribosylation; ATP-binding; Iron; Iron-sulfur; Metal-binding;
KW   Nitrogen fixation; Nucleotide-binding; Oxidoreductase.
FT   CHAIN           1..294
FT                   /note="Nitrogenase iron protein"
FT                   /id="PRO_0000139480"
FT   BINDING         13..20
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT                   /evidence="ECO:0000255"
FT   BINDING         101
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /ligand_note="ligand shared between dimeric partners"
FT                   /evidence="ECO:0000250"
FT   BINDING         135
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /ligand_note="ligand shared between dimeric partners"
FT                   /evidence="ECO:0000250"
FT   MOD_RES         104
FT                   /note="ADP-ribosylarginine; by dinitrogenase reductase ADP-
FT                   ribosyltransferase"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   294 AA;  32092 MW;  86BC996AC22B32CC CRC64;
     MTDENIRQIA FYGKGGIGKS TTSQNTLAAM AEMGQRIMIV GCDPKADSTR LMLHAKAQTT
     VLHLAAERGA VEDLELEEVM LTGFRGVKCV ESGGPEPGVG CAGRGIITAI NFLEENGAYQ
     DLDFVSYDVL GDVVCGGFAM PIREGKAQEI YIVTSGEMMA MYAANNIARG ILKYAHSGGV
     RLGGLICNSR KTDREAELIE NLAERLNTQM IHFVPRDNIV QHAELRRMTV NEYAPDSNQG
     QEYRALAKKI INNDKLTIPT PIEMDELEAL LIEYGILDDD TKHAEIIGKP ANAK
//