ID   B3QVT8_CHLT3            Unreviewed;       328 AA.
AC   B3QVT8;
DT   02-SEP-2008, integrated into UniProtKB/TrEMBL.
DT   02-SEP-2008, sequence version 1.
DT   10-JUN-2026, entry version 89.
DE   RecName: Full=Beta-ketoacyl-[acyl-carrier-protein] synthase III {ECO:0000256|HAMAP-Rule:MF_01815};
DE            Short=Beta-ketoacyl-ACP synthase III {ECO:0000256|HAMAP-Rule:MF_01815};
DE            Short=KAS III {ECO:0000256|HAMAP-Rule:MF_01815};
DE            EC=2.3.1.180 {ECO:0000256|HAMAP-Rule:MF_01815};
DE   AltName: Full=3-oxoacyl-[acyl-carrier-protein] synthase 3 {ECO:0000256|HAMAP-Rule:MF_01815};
DE   AltName: Full=3-oxoacyl-[acyl-carrier-protein] synthase III {ECO:0000256|HAMAP-Rule:MF_01815};
GN   Name=fabH {ECO:0000256|HAMAP-Rule:MF_01815};
GN   OrderedLocusNames=Ctha_0676 {ECO:0000313|EMBL:ACF13145.1};
OS   Chloroherpeton thalassium (strain ATCC 35110 / GB-78).
OC   Bacteria; Pseudomonadati; Chlorobiota; Chlorobiia; Chlorobiales;
OC   Chloroherpetonaceae; Chloroherpeton.
OX   NCBI_TaxID=517418 {ECO:0000313|EMBL:ACF13145.1, ECO:0000313|Proteomes:UP000001208};
RN   [1] {ECO:0000313|EMBL:ACF13145.1, ECO:0000313|Proteomes:UP000001208}
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC 35110 / GB-78 {ECO:0000313|Proteomes:UP000001208};
RG   US DOE Joint Genome Institute;
RA   Lucas S., Copeland A., Lapidus A., Glavina del Rio T., Dalin E., Tice H.,
RA   Bruce D., Goodwin L., Pitluck S., Schmutz J., Larimer F., Land M.,
RA   Hauser L., Kyrpides N., Mikhailova N., Liu Z., Li T., Zhao F., Overmann J.,
RA   Bryant D.A., Richardson P.;
RT   "Complete sequence of Chloroherpeton thalassium ATCC 35110.";
RL   Submitted (JUN-2008) to the EMBL/GenBank/DDBJ databases.
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:0000256|HAMAP-Rule:MF_01815}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=malonyl-[ACP] + acetyl-CoA + H(+) = 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:0000256|HAMAP-Rule:MF_01815};
CC   -!- PATHWAY: Lipid metabolism; fatty acid biosynthesis. {ECO:0000256|HAMAP-
CC       Rule:MF_01815}.
CC   -!- SUBUNIT: Homodimer. {ECO:0000256|HAMAP-Rule:MF_01815}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000256|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:0000256|HAMAP-
CC       Rule:MF_01815}.
CC   -!- SIMILARITY: Belongs to the thiolase-like superfamily. FabH family.
CC       {ECO:0000256|ARBA:ARBA00008642, ECO:0000256|HAMAP-Rule:MF_01815}.
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DR   EMBL; CP001100; ACF13145.1; -; Genomic_DNA.
DR   RefSeq; WP_012499229.1; NC_011026.1.
DR   AlphaFoldDB; B3QVT8; -.
DR   STRING; 517418.Ctha_0676; -.
DR   KEGG; cts:Ctha_0676; -.
DR   eggNOG; COG0332; Bacteria.
DR   HOGENOM; CLU_039592_3_1_10; -.
DR   OrthoDB; 9815506at2; -.
DR   UniPathway; UPA00094; -.
DR   Proteomes; UP000001208; 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   GO; GO:0044550; P:secondary metabolite biosynthetic process; IEA:TreeGrafter.
DR   CDD; cd00830; KAS_III; 1.
DR   FunFam; 3.40.47.10:FF:000004; 3-oxoacyl-[acyl-carrier-protein] synthase 3; 1.
DR   Gene3D; 3.40.47.10; -; 1.
DR   HAMAP; MF_01815; FabH; 1.
DR   InterPro; IPR013747; ACP_syn_III_C.
DR   InterPro; IPR013751; ACP_syn_III_N.
DR   InterPro; IPR004655; FabH.
DR   InterPro; IPR016039; Thiolase-like.
DR   NCBIfam; TIGR00747; fabH; 1.
DR   NCBIfam; NF006829; PRK09352.1; 1.
DR   PANTHER; PTHR34069; 3-OXOACYL-[ACYL-CARRIER-PROTEIN] SYNTHASE 3; 1.
DR   PANTHER; PTHR34069:SF2; BETA-KETOACYL-[ACYL-CARRIER-PROTEIN] SYNTHASE III; 1.
DR   Pfam; PF08545; ACP_syn_III; 1.
DR   Pfam; PF08541; ACP_syn_III_C; 1.
DR   SUPFAM; SSF53901; Thiolase-like; 1.
PE   3: Inferred from homology;
KW   Acyltransferase {ECO:0000256|ARBA:ARBA00023315, ECO:0000256|HAMAP-
KW   Rule:MF_01815}; Cytoplasm {ECO:0000256|HAMAP-Rule:MF_01815};
KW   Fatty acid biosynthesis {ECO:0000256|ARBA:ARBA00023160, ECO:0000256|HAMAP-
KW   Rule:MF_01815};
KW   Fatty acid metabolism {ECO:0000256|ARBA:ARBA00022832, ECO:0000256|HAMAP-
KW   Rule:MF_01815}; Lipid biosynthesis {ECO:0000256|HAMAP-Rule:MF_01815};
KW   Lipid metabolism {ECO:0000256|HAMAP-Rule:MF_01815};
KW   Multifunctional enzyme {ECO:0000256|ARBA:ARBA00023268, ECO:0000256|HAMAP-
KW   Rule:MF_01815}; Reference proteome {ECO:0000313|Proteomes:UP000001208};
KW   Transferase {ECO:0000256|ARBA:ARBA00022679, ECO:0000256|HAMAP-
KW   Rule:MF_01815}.
FT   DOMAIN          107..185
FT                   /note="Beta-ketoacyl-[acyl-carrier-protein] synthase III N-
FT                   terminal"
FT                   /evidence="ECO:0000259|Pfam:PF08545"
FT   DOMAIN          239..327
FT                   /note="Beta-ketoacyl-[acyl-carrier-protein] synthase III C-
FT                   terminal"
FT                   /evidence="ECO:0000259|Pfam:PF08541"
FT   REGION          255..259
FT                   /note="ACP-binding"
FT                   /evidence="ECO:0000256|HAMAP-Rule:MF_01815"
FT   ACT_SITE        113
FT                   /evidence="ECO:0000256|HAMAP-Rule:MF_01815"
FT   ACT_SITE        254
FT                   /evidence="ECO:0000256|HAMAP-Rule:MF_01815"
FT   ACT_SITE        284
FT                   /evidence="ECO:0000256|HAMAP-Rule:MF_01815"
SQ   SEQUENCE   328 AA;  35679 MW;  EDD9C4C35CBC650F CRC64;
     MKAAITATAK YTPPDKLTNF DLEKILDTND EWIRTRTGIQ ERRILKDPDK ATAYMCAEVS
     KQILEKRGIS AEEIDLIIIG TVTPDTIFPA AGCLVQGMIG AKNAWAFDLS AACSGFLYSL
     VVGSQFIESG MHKKVLVLGA DKMSAITDFT DRNTAVLFGD GAGGVLLEPA KDGYGVLDAK
     LYADGANGKD HLYMLAGGSL RPPSHETVDK KMHAIRQDGR VVFKSAVTEM ANSAVEMMRR
     NNLSADDITY LIPHQANHRI IMATAERMNI SMDKVGINID RYGNTTAATI PLCLAELDES
     GKLKSGDNLI FVSFGAGYTW GGIYVKWQ
//