ID   FABH_PROMP              Reviewed;         335 AA.
AC   Q7V3E0;
DT   26-APR-2004, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2003, sequence version 1.
DT   25-MAY-2022, entry version 105.
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=PMM0136;
OS   Prochlorococcus marinus subsp. pastoris (strain CCMP1986 / NIES-2087 /
OS   MED4).
OC   Bacteria; Cyanobacteria; Synechococcales; Prochlorococcaceae;
OC   Prochlorococcus.
OX   NCBI_TaxID=59919;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=CCMP1986 / NIES-2087 / MED4;
RX   PubMed=12917642; DOI=10.1038/nature01947;
RA   Rocap G., Larimer F.W., Lamerdin J.E., Malfatti S., Chain P., Ahlgren N.A.,
RA   Arellano A., Coleman M., Hauser L., Hess W.R., Johnson Z.I., Land M.L.,
RA   Lindell D., Post A.F., Regala W., Shah M., Shaw S.L., Steglich C.,
RA   Sullivan M.B., Ting C.S., Tolonen A., Webb E.A., Zinser E.R.,
RA   Chisholm S.W.;
RT   "Genome divergence in two Prochlorococcus ecotypes reflects oceanic niche
RT   differentiation.";
RL   Nature 424:1042-1047(2003).
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; BX548174; CAE18595.1; -; Genomic_DNA.
DR   RefSeq; WP_011131775.1; NC_005072.1.
DR   AlphaFoldDB; Q7V3E0; -.
DR   SMR; Q7V3E0; -.
DR   STRING; 59919.PMM0136; -.
DR   EnsemblBacteria; CAE18595; CAE18595; PMM0136.
DR   KEGG; pmm:PMM0136; -.
DR   eggNOG; COG0332; Bacteria.
DR   HOGENOM; CLU_039592_0_1_3; -.
DR   OMA; WGSEGDK; -.
DR   OrthoDB; 872193at2; -.
DR   UniPathway; UPA00094; -.
DR   Proteomes; UP000001026; Chromosome.
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..335
FT                   /note="3-oxoacyl-[acyl-carrier-protein] synthase 3"
FT                   /id="PRO_0000110454"
FT   REGION          262..266
FT                   /note="ACP-binding"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        119
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        261
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
FT   ACT_SITE        291
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01815"
SQ   SEQUENCE   335 AA;  36465 MW;  968F6A23DB007938 CRC64;
     MEGINLNQIG VSFKGSGSYV PNQILTNQEI SKKVETSDEW IKSRTGISQR RISGLSENVS
     EMGYKAALGA IEMARWDIET IDLIILATST PNDLFGSAPE IQSKLGAINA VAFDLTAACS
     GFLFAAITAT QFLKAGSYKR AVVIGSDQLS SYVDWNDRRS CILFGDGAGA IAIEGTNELD
     NLLGFSMRTD GQRGSFLNLP SQNNQDLIIN DINFSSGGFS SIKMNGQEVY KFAVREVPLI
     IDNLFKKTNF NSEKINWLLL HQANQRILDS VGERLNVSTE KILSNLSNYG NTSAATIPLM
     LDEAIRNKKI KENDIIATSG FGAGLSWGAA LIRWG