ID   ANFD_HELGE              Reviewed;         280 AA.
AC   O68955;
DT   15-JUL-1999, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1998, sequence version 1.
DT   03-AUG-2022, entry version 81.
DE   RecName: Full=Nitrogenase iron-iron protein alpha chain;
DE            EC=1.18.6.1;
DE   AltName: Full=Dinitrogenase 3 subunit alpha;
DE   AltName: Full=Nitrogenase component I;
DE   Flags: Fragment;
GN   Name=anfD;
OS   Heliomicrobium gestii (Heliobacterium gestii).
OC   Bacteria; Firmicutes; Clostridia; Eubacteriales; Heliobacteriaceae;
OC   Heliomicrobium.
OX   NCBI_TaxID=2699;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=10420583; DOI=10.1139/w99-007;
RA   Loveless T.M., Bishop P.E.;
RT   "Identification of genes unique to Mo-independent nitrogenase systems in
RT   diverse diazotrophs.";
RL   Can. J. Microbiol. 45:312-317(1999).
CC   -!- FUNCTION: This iron-iron protein is part of the nitrogenase complex
CC       that catalyzes the key enzymatic reactions in nitrogen fixation. Other
CC       nitrogenase complexes utilize a molybdenum-iron protein or a vanadium-
CC       iron protein.
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   -!- COFACTOR:
CC       Name=[8Fe-9S-C-homocitryl] cluster; Xref=ChEBI:CHEBI:60504;
CC         Evidence={ECO:0000250};
CC       Note=Binds 1 [8Fe-9S-C-homocitryl] cluster per subunit. {ECO:0000250};
CC   -!- SUBUNIT: Hexamer of two alpha, two beta, and two delta chains.
CC       {ECO:0000250}.
CC   -!- MISCELLANEOUS: The structure of the 8Fe-9S-C-homocitryl cluster is
CC       assumed to be analogous to the 7Fe-Mo-9S-C-homocitryl cluster.
CC   -!- SIMILARITY: Belongs to the NifD/NifK/NifE/NifN family. {ECO:0000305}.
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DR   EMBL; AF058785; AAC14342.1; -; Genomic_DNA.
DR   AlphaFoldDB; O68955; -.
DR   SMR; O68955; -.
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; IPR005974; Nase_asu.
DR   InterPro; IPR010143; Nase_comp1_asu.
DR   InterPro; IPR000318; Nase_comp1_CS.
DR   PANTHER; PTHR43457; PTHR43457; 1.
DR   Pfam; PF00148; Oxidored_nitro; 1.
DR   TIGRFAMs; TIGR01284; alt_nitrog_alph; 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..>280
FT                   /note="Nitrogenase iron-iron protein alpha chain"
FT                   /id="PRO_0000153067"
FT   BINDING         5
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with beta chain"
FT                   /evidence="ECO:0000250"
FT   BINDING         31
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with beta chain"
FT                   /evidence="ECO:0000250"
FT   BINDING         94
FT                   /ligand="[8Fe-7S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:21143"
FT                   /ligand_note="ligand shared with beta chain"
FT                   /evidence="ECO:0000250"
FT   BINDING         213
FT                   /ligand="[8Fe-9S-C-homocitryl] cluster"
FT                   /ligand_id="ChEBI:CHEBI:60504"
FT                   /evidence="ECO:0000250"
FT   NON_TER         1
FT   NON_TER         280
SQ   SEQUENCE   280 AA;  31772 MW;  CDF25376AF1056A1 CRC64;
     SERGCAYCGA KHVIGTPMKD VIHISHGPVG CTYDTWQTKR YISDNDNFQL KYTYATDMKE
     KHIVFGAEKL LKKNIIEAFQ AFPDIKRMTI YQTCASALIG DDINAIAQEV MDELPDVDIF
     VCNSPGFAGP SQSGGHHKIN IAWIDQKVGT VEPKITSDYV INYVGEYNIQ GDQEVMLDYF
     KRMGIQVLST FTGNGSYDDL RAMHRAHLNV LECARSAEYI CNELRVRYGI PRLDIDGFGF
     EPLSTSLRKI GLFFGIEDRA QAIIEEETAR WKPELDWYKE