ID   FABH_POLNS              Reviewed;         328 AA.
AC   B1XTK6;
DT   28-JUL-2009, integrated into UniProtKB/Swiss-Prot.
DT   20-MAY-2008, sequence version 1.
DT   25-MAY-2022, entry version 72.
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=Pnec_0405;
OS   Polynucleobacter necessarius subsp. necessarius (strain STIR1).
OC   Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales;
OC   Burkholderiaceae; Polynucleobacter.
OX   NCBI_TaxID=452638;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=STIR1;
RX   PubMed=24167248; DOI=10.1073/pnas.1316687110;
RA   Boscaro V., Felletti M., Vannini C., Ackerman M.S., Chain P.S.,
RA   Malfatti S., Vergez L.M., Shin M., Doak T.G., Lynch M., Petroni G.;
RT   "Polynucleobacter necessarius, a model for genome reduction in both free-
RT   living and symbiotic bacteria.";
RL   Proc. Natl. Acad. Sci. U.S.A. 110:18590-18595(2013).
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: Cytoplasm {ECO:0000255|HAMAP-Rule:MF_01815}.
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; CP001010; ACB43683.1; -; Genomic_DNA.
DR   RefSeq; WP_012357450.1; NC_010531.1.
DR   AlphaFoldDB; B1XTK6; -.
DR   SMR; B1XTK6; -.
DR   STRING; 452638.Pnec_0405; -.
DR   EnsemblBacteria; ACB43683; ACB43683; Pnec_0405.
DR   KEGG; pne:Pnec_0405; -.
DR   eggNOG; COG0332; Bacteria.
DR   HOGENOM; CLU_039592_3_1_4; -.
DR   OMA; WGSEGDK; -.
DR   OrthoDB; 872193at2; -.
DR   UniPathway; UPA00094; -.
DR   GO; GO:0005737; C:cytoplasm; 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; Cytoplasm; Fatty acid biosynthesis; Fatty acid metabolism;
KW   Lipid biosynthesis; Lipid metabolism; Multifunctional enzyme; Transferase.
FT   CHAIN           1..328
FT                   /note="3-oxoacyl-[acyl-carrier-protein] synthase 3"
FT                   /id="PRO_1000187887"
FT   REGION          256..260
FT                   /note="ACP-binding"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        122
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   328 AA;  34612 MW;  9CB0D4226CD6CC7A CRC64;
     MSIFARVAGT GSYLPELRLT NQDLVERLAK TGLETSDEWI KTRSGISARH FAAENELTSD
     LAVRAAEAAL SSTGINSADL DLIILATSTP DHLGGFPSTA CVVQDKLGAH TSCAAFDVQA
     VCAGFTYALA VADAFIRSGS YKKVLVIGAE TFSRILNFQD RGTCVLFGDG AGAVVLEASK
     EAGILSTVMH ADGSQRDILC VPGRAGNGEV RGSPFMTMDG QAVFKLAVKV LEQVAHEALD
     KAKLKPEQID WLVPHQANIR IMEGTAKKMG MSMDKVIVTV HEHGNTSAAS IPLALDSGVR
     SGQIKRGQHL LLEGVGGGFA WGAVAIKY