ID   FABH_GRATL              Reviewed;         330 AA.
AC   Q6B945;
DT   21-JUN-2005, integrated into UniProtKB/Swiss-Prot.
DT   13-SEP-2004, sequence version 1.
DT   25-MAY-2022, entry version 71.
DE   RecName: Full=3-oxoacyl-[acyl-carrier-protein] synthase 3 {ECO:0000255|HAMAP-Rule:MF_01815};
DE            EC=2.3.1.180 {ECO:0000255|HAMAP-Rule:MF_01815};
DE   AltName: Full=3-oxoacyl-[acyl-carrier-protein] synthase III {ECO:0000255|HAMAP-Rule:MF_01815};
DE   AltName: Full=Beta-ketoacyl-ACP synthase III {ECO:0000255|HAMAP-Rule:MF_01815};
DE            Short=KAS III {ECO:0000255|HAMAP-Rule:MF_01815};
GN   Name=fabH {ECO:0000255|HAMAP-Rule:MF_01815}; OrderedLocusNames=Grc000008;
OS   Gracilaria tenuistipitata var. liui (Red alga).
OG   Plastid; Chloroplast.
OC   Eukaryota; Rhodophyta; Florideophyceae; Rhodymeniophycidae; Gracilariales;
OC   Gracilariaceae; Agarophyton; Agarophyton tenuistipitatum.
OX   NCBI_TaxID=285951;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RX   PubMed=15638458; DOI=10.1007/s00239-004-2638-3;
RA   Hagopian J.C., Reis M., Kitajima J.P., Bhattacharya D., de Oliveira M.C.;
RT   "Comparative analysis of the complete plastid genome sequence of the red
RT   alga Gracilaria tenuistipitata var. liui provides insights into the
RT   evolution of rhodoplasts and their relationship to other plastids.";
RL   J. Mol. Evol. 59:464-477(2004).
CC   -!- FUNCTION: Catalyzes the condensation reaction of fatty acid synthesis
CC       by the addition to an acyl acceptor of two carbons from malonyl-ACP.
CC       Catalyzes the first condensation reaction which initiates fatty acid
CC       synthesis and may therefore play a role in governing the total rate of
CC       fatty acid production. Possesses both acetoacetyl-ACP synthase and
CC       acetyl transacylase activities. Its substrate specificity determines
CC       the biosynthesis of branched-chain and/or straight-chain of fatty
CC       acids. {ECO:0000255|HAMAP-Rule:MF_01815}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=acetyl-CoA + H(+) + malonyl-[ACP] = 3-oxobutanoyl-[ACP] + CO2
CC         + CoA; Xref=Rhea:RHEA:12080, Rhea:RHEA-COMP:9623, Rhea:RHEA-
CC         COMP:9625, ChEBI:CHEBI:15378, ChEBI:CHEBI:16526, ChEBI:CHEBI:57287,
CC         ChEBI:CHEBI:57288, ChEBI:CHEBI:78449, ChEBI:CHEBI:78450;
CC         EC=2.3.1.180; Evidence={ECO:0000255|HAMAP-Rule:MF_01815};
CC   -!- PATHWAY: Lipid metabolism; fatty acid biosynthesis. {ECO:0000255|HAMAP-
CC       Rule:MF_01815}.
CC   -!- SUBUNIT: Homodimer. {ECO:0000255|HAMAP-Rule:MF_01815}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast.
CC   -!- DOMAIN: The last Arg residue of the ACP-binding site is essential for
CC       the weak association between ACP/AcpP and FabH. {ECO:0000255|HAMAP-
CC       Rule:MF_01815}.
CC   -!- SIMILARITY: Belongs to the thiolase-like superfamily. FabH family.
CC       {ECO:0000255|HAMAP-Rule:MF_01815}.
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DR   EMBL; AY673996; AAT79590.1; -; Genomic_DNA.
DR   RefSeq; YP_063515.1; NC_006137.1.
DR   AlphaFoldDB; Q6B945; -.
DR   SMR; Q6B945; -.
DR   GeneID; 2943979; -.
DR   UniPathway; UPA00094; -.
DR   GO; GO:0009507; C:chloroplast; IEA:UniProtKB-SubCell.
DR   GO; GO:0004315; F:3-oxoacyl-[acyl-carrier-protein] synthase activity; IEA:InterPro.
DR   GO; GO:0033818; F:beta-ketoacyl-acyl-carrier-protein synthase III activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0006633; P:fatty acid biosynthetic process; IEA:UniProtKB-UniRule.
DR   Gene3D; 3.40.47.10; -; 1.
DR   HAMAP; MF_01815; FabH; 1.
DR   InterPro; IPR013751; ACP_syn_III.
DR   InterPro; IPR013747; ACP_syn_III_C.
DR   InterPro; IPR004655; FabH_synth.
DR   InterPro; IPR016039; Thiolase-like.
DR   Pfam; PF08545; ACP_syn_III; 1.
DR   Pfam; PF08541; ACP_syn_III_C; 1.
DR   SUPFAM; SSF53901; SSF53901; 1.
DR   TIGRFAMs; TIGR00747; fabH; 1.
PE   3: Inferred from homology;
KW   Acyltransferase; Chloroplast; Fatty acid biosynthesis;
KW   Fatty acid metabolism; Lipid biosynthesis; Lipid metabolism;
KW   Multifunctional enzyme; Plastid; Transferase.
FT   CHAIN           1..330
FT                   /note="3-oxoacyl-[acyl-carrier-protein] synthase 3"
FT                   /id="PRO_0000110516"
FT   REGION          256..260
FT                   /note="ACP-binding"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        113
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        255
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        285
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
SQ   SEQUENCE   330 AA;  36075 MW;  4DF9347E04164614 CRC64;
     MQGAQIISIG SAVPDLCINN KEISQIVETS DEWIVTRTGI QERRVLTGTN KSVVDLAYSA
     AMKALDKIHM DPLEIDLIIL ATSSPNDLFG SASQVQAKIG AARAVAFDLT AACSGFVLAI
     VTATQFIQNG SYKNILIIGA DVLSKWIDWS DRKTCILFGD GAGAAIIQAC YEEDNAILGF
     QLNTDGKQYK KLSITYKENN YSLNTLKLFQ GQFQYISMNG KEVYKFAVSK VPASIIKCLN
     ALHLSIQDVN WLLLHQANKR ILQAVANRLS VDNYKIISNL SKYGNTSAAS IPLALDEAWQ
     NNQIAKEDII VISGFGAGLT WGTVVIKWKC