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Information on EC 2.3.1.300 - branched-chain beta-ketoacyl-[acyl-carrier-protein] synthase
for references in articles please use BRENDA:EC2.3.1.300
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EC Tree 2 Transferases
2.3 Acyltransferases
2.3.1 Transferring groups other than aminoacyl groups
2.3.1.300 branched-chain beta-ketoacyl-[acyl-carrier-protein] synthase
IUBMB Comments
The enzyme is responsible for initiating branched-chain fatty acid biosynthesis by the dissociated (or type II) fatty-acid biosynthesis system (FAS-II) in some bacteria, using molecules derived from degradation of the branched-chain amino acids L-leucine, L-valine, and L-isoleucine to form the starting molecules for elongation by the FAS-II system. In some organisms the enzyme is also able to use acetyl-CoA, leading to production of a mix of branched-chain and straight-chain fatty acids (cf. EC 2.3.1.180, β-ketoacyl-[acyl-carrier-protein] synthase III).
The enzyme appears in viruses and cellular organisms
Reaction Schemes
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a 5-methyl-3-oxohexanoyl-[acyl-carrier-protein]
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a 4-methyl-3-oxopentanoyl-[acyl-carrier-protein]
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a (4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein]
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Synonyms
3-oxoacyl-[acyl-carrier-protein] synthase, FabH, FabH1, FabH2, FabHA, FabHB, KAS III, LMRG_01630, more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
FabH
FabH1
FabH2
FabHA
FabHB
KAS III
LMRG_01630
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
(2S)-2-methylbutanoyl-CoA + a malonyl-[acyl-carrier protein] = a (4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
(3)
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2-methylpropanoyl-CoA + a malonyl-[acyl-carrier protein] = a 4-methyl-3-oxopentanoyl-[acyl-carrier-protein] + CoA + CO2
(2)
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3-methylbutanoyl-CoA + a malonyl-[acyl-carrier protein] = a 5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
(1)
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PATHWAY SOURCE
PATHWAYS
MetaCyc
anteiso-branched-chain fatty acid biosynthesis, even iso-branched-chain fatty acid biosynthesis, odd iso-branched-chain fatty acid biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
3-methylbutanoyl-CoA:malonyl-[acyl-carrier protein] C-acyltransferase
The enzyme is responsible for initiating branched-chain fatty acid biosynthesis by the dissociated (or type II) fatty-acid biosynthesis system (FAS-II) in some bacteria, using molecules derived from degradation of the branched-chain amino acids L-leucine, L-valine, and L-isoleucine to form the starting molecules for elongation by the FAS-II system. In some organisms the enzyme is also able to use acetyl-CoA, leading to production of a mix of branched-chain and straight-chain fatty acids [3] (cf. EC 2.3.1.180, beta-ketoacyl-[acyl-carrier-protein] synthase III).
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
(2S)-2-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
(4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
2-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
2-methylpropanoyl-CoA + malonyl-[acyl-carrier protein]
4-methyl-3-oxopentanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
3-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
ethyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
acetyl-CoA + malonyl-[acyl-carrier protein]
3-oxobutanoyl-[acyl-carrier protein] + CoA + CO2
Substrates: -
Products: -
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?
butanoyl-CoA + malonyl-[acyl-carrier protein]
3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
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isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
isobutanoyl-CoA + malonyl-[FabC]
5-methyl-3-oxohexanoyl-[FabC] + CoA + CO2
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Substrates: -
Products: -
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isobutanoyl-CoA + malonyl-[RedQ]
5-methyl-3-oxohexanoyl-[RedQ] + CoA + CO2
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Substrates: malonyl-[RedQ] is involved in undecylprodiginine biosynthesis
Products: -
Products: -
?
(2S)-2-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
(4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
(2S)-2-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
(4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
(2S)-2-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
(4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
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?
isohexanoyl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
Products: -
?
isohexanoyl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
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?
isovaleryl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
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isovaleryl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
Products: -
?
isovaleryl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
Products: -
?
isovaleryl-CoA + malonyl-[acyl-carrier protein]
? + CoA + CO2
Substrates: -
Products: -
Products: -
?
additional information
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Substrates: KAS III has distinctive substrate specificity and uses branched-chain acyl-CoA as well as long-chain acyl-CoA. KAS III can use butanoyl-, isobutanoyl-, and hexanoyl-CoA as preferred substrates over acetyl-CoA (reaction of EC 32.3.1.180)
Products: -
Products: -
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additional information
?
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Substrates: KAS III has distinctive substrate specificity and uses branched-chain acyl-CoA as well as long-chain acyl-CoA. KAS III can use butanoyl-, isobutanoyl-, and hexanoyl-CoA as preferred substrates over acetyl-CoA (reaction of EC 32.3.1.180)
Products: -
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additional information
?
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Substrates: the order of catalytic efficiency (in decreasing order) is: 2-methylbutyryl-CoA, isovaleryl-CoA, isobutyryl-CoA, acetyl-CoA
Products: -
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additional information
?
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Substrates: the order of catalytic efficiency (in decreasing order) is: 2-methylbutyryl-CoA, isovaleryl-CoA, isobutyryl-CoA, acetyl-CoA
Products: -
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additional information
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Substrates: enzyme demonstrates both beta-ketoacyl-acyl carrier protein synthase activity and acyl coenzyme A:acyl carrier protein transacylase activity in a 1:0.12 ratio
Products: -
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additional information
?
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Substrates: FabH in addition uses acetyl-CoA, butanoyl-CoA, hexanoyl-CoA, octanoyl-CoA, or decanoyl-CoA as a primer as a primer to initiate fatty acid synthesis, reaction of EC 2.3.1.180, and also condenses short-chain acyl-ACPs with malonyl-ACP to produce longer acyl-ACPs
Products: -
Products: -
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
(2S)-2-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
(4S)-4-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
2-methylpropanoyl-CoA + malonyl-[acyl-carrier protein]
4-methyl-3-oxopentanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
3-methylbutanoyl-CoA + malonyl-[acyl-carrier protein]
ethyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
acetyl-CoA + malonyl-[acyl-carrier protein]
3-oxobutanoyl-[acyl-carrier protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
butanoyl-CoA + malonyl-[acyl-carrier protein]
3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
isobutanoyl-CoA + malonyl-[acyl-carrier protein]
5-methyl-3-oxohexanoyl-[acyl-carrier-protein] + CoA + CO2
Substrates: -
Products: -
Products: -
?
additional information
?
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Substrates: enzyme demonstrates both beta-ketoacyl-acyl carrier protein synthase activity and acyl coenzyme A:acyl carrier protein transacylase activity in a 1:0.12 ratio
Products: -
Products: -
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
11350
substrate isobutanoyl-CoA, pH 7, temperature not specified in the publication
17350
substrate isovaleryl-CoA, pH 7, temperature not specified in the publication
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Highest Expressing Human Cell Lines
Cell Line LinksPlease wait a moment until the data is sorted. This message will disappear when the data is sorted.
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
physiological function
physiological function
FabH is able to condense branched-chain acyl-CoAs with malonyl-ACP to initiate branched-chain fatty acid synthesis. The fabH gene is essential for growth of Xanthomonas campestris. It can be replaced with Escherichia coli fabH, and transgenic strains mutants fail to produce branched-chain fatty acids. Xanthomonas campestris FabH mutants lost the ability to produce cis-11-methyl-2-dodecenoic acid
physiological function
FabH is responsible for initiating both straight- and branched-chain fatty acid biosynthesis in Streptomyces glaucescens and the ratio of the various fatty acids produced will be dictated by the ratios of the various acyl-CoA substrates that can react with FabH
physiological function
-
replacement of the acetyl-CoA-specific Escherichia coli FabH with branched-chain-acyl-CoA-specific Staphylococcus aureus FabH increases the synthesis of branched-chain fatty acids, resulting in a significant enhancement in branched-chain fatty acids titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs
physiological function
-
replacementof the acetyl-CoA-specific Escherichia coli FabH with branched-chain-acyl-CoA-specific Bacillus subtilis FabH1 increases the synthesis of branched-chain fatty acids, resulting in a significant enhancement in branched-chain fatty acids titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs
physiological function
-
replacementof the acetyl-CoA-specific Escherichia coli FabH with branched-chain-acyl-CoA-specific Bacillus subtilis FabH2 increases the synthesis of branched-chain fatty acids, resulting in a significant enhancement in branched-chain fatty acids titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs
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UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). C0LNR0_LISM4
Listeria monocytogenes serotype 1/2a (strain 10403S)
312
0
33971
TrEMBL
-
FABH_XANC8
Xanthomonas campestris pv. campestris (strain 8004)
325
0
34692
Swiss-Prot
-
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
C122A
C122A
mutation of active-site residue, mutant displays much improved solubility
C122A
-
mutation of active-site residue, mutant displays much improved solubility
-
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
synthesis
synthesis
-
replacement of the acetyl-CoA-specific Escherichia coli FabH with branched-chain-acyl-CoA-specific Bacillus subtilis FabH1 increases the synthesis of branched-chain fatty acids, resulting in a significant enhancement in branched-chain fatty acids titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs. The titer of branched-chain fatty acids reaches 19.4 mg/L. The composition of branched-chain fatty acids can be tuned by engineering the upstream pathway to control the supply of different branched-chain acyl-CoAs, leading to the production either even-chain-iso-, odd-chain-iso-, or odd-chain-anteiso-branched-chain fatty acids separately
synthesis
-
replacement of the acetyl-CoA-specific Escherichia coli FabH with branched-chain-acyl-CoA-specific Bacillus subtilis FabH2 increases the synthesis of branched-chain fatty acids, resulting in a significant enhancement in branched-chain fatty acids titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs. The titer of branched-chain fatty acids reaches 17.5 mg/L. The composition of branched-chain fatty acids can be tuned by engineering the upstream pathway to control the supply of different branched-chain acyl-CoAs, leading to the production either even-chain-iso-, odd-chain-iso-, or odd-chain-anteiso-branched-chain fatty acids separately
synthesis
-
replacement of the acetyl-CoA-specific Escherichia coli FabH with branched-chain-acyl-CoA-specific Staphylococcus aureus FabH increases the synthesis of branched-chain fatty acids, resulting in a significant enhancement in branched-chain fatty acids titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs. The titer of branched-chain fatty acids reaches 40.3 mg/L. The composition of branched-chain fatty acids can be tuned by engineering the upstream pathway to control the supply of different branched-chain acyl-CoAs, leading to the production either even-chain-iso-, odd-chain-iso-, or odd-chain-anteiso-branched-chain fatty acids separately
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REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Cheon, D.; Lee, W.; Lee, Y.; Lee, J.; Kim, Y.
Structural basis of branched-chain fatty acid synthesis by Propionibacterium acnes beta-ketoacyl acyl carrier protein synthase
Biochem. Biophys. Res. Commun.
509
322-328
2019
Cutibacterium acnes (A0A2B7IGT3), Cutibacterium acnes KPA171202 (A0A2B7IGT3)
brenda
Jiang, W.; Jiang, Y.; Bentley, G.; Liu, D.; Xiao, Y.; Zhang, F.
Enhanced production of branched-chain fatty acids by replacing beta-ketoacyl-(acyl-carrier-protein) synthase III (FabH)
Biotechnol. Bioeng.
112
1613-1622
2015
Bacillus subtilis, Staphylococcus aureus
brenda
Singh, A.; Zhang, Y.; Zhu, K.; Subramanian, C.; Li, Z.; Jayaswal, R.; Gatto, C.; Rock, C.; Wilkinson, B.
FabH selectivity for anteiso branched-chain fatty acid precursors in low-temperature adaptation in Listeria monocytogenes
FEMS Microbiol. Lett.
301
188-192
2009
Listeria monocytogenes serotype 1/2a (C0LNR0), Listeria monocytogenes serotype 1/2a 10403S (C0LNR0)
brenda
Singh, R.; Mo, S.; Florova, G.; Reynolds, K.
Streptomyces coelicolor RedP and FabH enzymes, initiating undecylprodiginine and fatty acid biosynthesis, exhibit distinct acyl-CoA and malonyl-acyl carrier protein substrate specificities
FEMS Microbiol. Lett.
328
32-38
2012
Streptomyces coelicolor
brenda
Han, L.; Lobo, S.; Reynolds, K.
Characterization of beta-ketoacyl-acyl carrier protein synthase III from Streptomyces glaucescens and its role in initiation of fatty acid biosynthesis
J. Bacteriol.
180
4481-4486
1998
Streptomyces glaucescens (Q54206)
brenda
Choi, K.; Heath, R.; Rock, C.
beta-Ketoacyl-acyl carrier protein synthase III (FabH) is a determining factor in branched-chain fatty acid biosynthesis
J. Bacteriol.
182
365-370
2000
Bacillus subtilis (O07600), Bacillus subtilis (O34746), Bacillus subtilis 168 (O07600), Bacillus subtilis 168 (O34746)
brenda
Yu, Y.; Hu, Z.; Dong, H.; Ma, J.; Wang, H.
Xanthomonas campestris FabH is required for branched-chain fatty acid and DSF-family quorum sensing signal biosynthesis
Sci. Rep.
6
32811
2016
Xanthomonas campestris pv. campestris (Q4URQ0)
brenda
EXTERNAL LINKS (specific for EC-Number 2.3.1.300)
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Release 2023.1 (January 2023)
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