ID   NIFH_NOSS6              Reviewed;         295 AA.
AC   Q51296;
DT   23-JAN-2002, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   03-AUG-2022, entry version 99.
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   Nostoc sp. (strain PCC 6720) (Anabaenopsis circularis).
OC   Bacteria; Cyanobacteria; Nostocales; Nostocaceae; Nostoc.
OX   NCBI_TaxID=34077;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=7918657; DOI=10.1016/0167-4781(94)90086-8;
RA   Beesley C.E., Smith R.J., Temple S.J., Lea P.J.;
RT   "Cloning and nucleotide sequence of the gene encoding dinitrogenase
RT   reductase (nifH) from the cyanobacterium Nostoc 6720.";
RL   Biochim. Biophys. Acta 1219:548-550(1994).
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=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=[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; Z31716; CAA83510.1; -; Genomic_DNA.
DR   PIR; S50135; S50135.
DR   AlphaFoldDB; Q51296; -.
DR   SMR; Q51296; -.
DR   GO; GO:0051539; F:4 iron, 4 sulfur cluster binding; IEA:UniProtKB-KW.
DR   GO; GO:0005524; F:ATP binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0018697; F:carbonyl sulfide nitrogenase activity; IEA:UniProtKB-EC.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0016163; F:nitrogenase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0009399; P:nitrogen fixation; IEA:UniProtKB-UniRule.
DR   Gene3D; 3.40.50.300; -; 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   PANTHER; PTHR42864; PTHR42864; 1.
DR   Pfam; PF00142; Fer4_NifH; 1.
DR   PIRSF; PIRSF000363; Nitrogenase_iron; 1.
DR   SUPFAM; SSF52540; SSF52540; 1.
DR   TIGRFAMs; TIGR01287; nifH; 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..295
FT                   /note="Nitrogenase iron protein"
FT                   /id="PRO_0000139516"
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   295 AA;  32230 MW;  4A3A913E6E78A3E0 CRC64;
     MTDENIRQIA FYGKGGIGKS TTSQNTLAAM AEMGQRIMIV GCDPKADSTR LMLHAKAKTT
     VLHLAAERGA VEDLELHEVM LTGFRGVRCV ESGGPEPGVG CAGRGIITAI NFLEENGAYQ
     DLDFVSYDVL GDVVCGGFAM PIREGKAQEI YIVTSGEMMA MYAANNIARG ILKYAHSGGV
     RLGGLICNSR KTDREAELIE NLAERLNTQM IHFVPRDNIV QHAELRRMTV NEYAPDSNQG
     QEYRALAKKI INNDKLTIPT PIEMDELEAL LIEYGILDDD SKHAEIIGKP AEATK