ExplorEnz: EC 2.3.1.41

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2.3.1.41

Accepted name:

β-ketoacyl-[acyl-carrier-protein] synthase I

Reaction:

an acyl-[acyl-carrier protein] + a malonyl-[acyl-carrier protein] = a 3-oxoacyl-[acyl-carrier protein] + CO₂ + an [acyl-carrier protein]

Glossary:

acyl-[acyl-carrier protein] = R-CO-[acyl-carrier protein]
malonyl-[acyl-carrier protein] = HOOC-CH₂-CO-[acyl-carrier protein]
3-oxoacyl-[acyl-carrier protein] = R-CO-CH₂-CO-[acyl-carrier protein]

Other name(s):

β-ketoacyl-ACP synthase I; β-ketoacyl synthetase; β-ketoacyl-ACP synthetase; β-ketoacyl-acyl carrier protein synthetase; β-ketoacyl-[acyl carrier protein] synthase; β-ketoacylsynthase; condensing enzyme (ambiguous); 3-ketoacyl-acyl carrier protein synthase; fatty acid condensing enzyme; acyl-malonyl(acyl-carrier-protein)-condensing enzyme; acyl-malonyl acyl carrier protein-condensing enzyme; β-ketoacyl acyl carrier protein synthase; 3-oxoacyl-[acyl-carrier-protein] synthase; 3-oxoacyl:ACP synthase I; KASI; KAS I; FabF1; FabB; acyl-[acyl-carrier-protein]:malonyl-[acyl-carrier-protein] C-acyltransferase (decarboxylating)

Systematic name:

acyl-[acyl-carrier protein]:malonyl-[acyl-carrier protein] C-acyltransferase (decarboxylating)

Comments:

This enzyme is responsible for the chain-elongation step of dissociated (type II) fatty-acid biosynthesis, i.e. the addition of two C atoms to the fatty-acid chain. Escherichia coli mutants that lack this enzyme are deficient in unsaturated fatty acids. The enzyme can use fatty acyl thioesters of ACP (C₂ to C₁₆) as substrates, as well as fatty acyl thioesters of Co-A (C₄ to C₁₆) [4]. The substrate specificity is very similar to that of EC 2.3.1.179, β-ketoacyl-ACP synthase II, with the exception that the latter enzyme is far more active with palmitoleoyl-ACP (C16Δ⁹) as substrate, allowing the organism to regulate its fatty-acid composition with changes in temperature [4,5].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9077-10-5

References:

1.	Alberts, A.W., Majerus, P.W. and Vagelos, P.R. Acetyl-CoA acyl carrier protein transacylase. Methods Enzymol. 14 (1969) 50–53. [DOI]
2.	Prescott, D.J. and Vagelos, P.R. Acyl carrier protein. Adv. Enzymol. Relat. Areas Mol. Biol. 36 (1972) 269–311. [DOI] [PMID: 4561013]
3.	Toomey, R.E. and Wakil, S.J. Studies on the mechanism of fatty acid synthesis. XVI. Preparation and general properties of acyl-malonyl acyl carrier protein-condensing enzyme from Escherichia coli. J. Biol. Chem. 241 (1966) 1159–1165. [PMID: 5327099]
4.	D'Agnolo, G., Rosenfeld, I.S. and Vagelos, P.R. Multiple forms of β-ketoacyl-acyl carrier protein synthetase in Escherichia coli. J. Biol. Chem. 250 (1975) 5289–5294. [PMID: 237914]
5.	Garwin, J.L., Klages, A.L. and Cronan, J.E., Jr.. Structural, enzymatic, and genetic studies of β-ketoacyl-acyl carrier protein synthases I and II of Escherichia coli. J. Biol. Chem. 255 (1980) 11949–11956. [PMID: 7002930]
6.	Wang, H. and Cronan, J.E. Functional replacement of the FabA and FabB proteins of Escherichia coli fatty acid synthesis by Enterococcus faecalis FabZ and FabF homologues. J. Biol. Chem. 279 (2004) 34489–34495. [DOI] [PMID: 15194690]
7.	Cronan, J.E., Jr. and Rock, C.O. Biosynthesis of membrane lipids. In: Neidhardt, F.C. (Ed.), Escherichia coli and Salmonella: Cellular and Molecular Biology, 2nd edn, vol. 1, ASM Press, Washington, DC, 1996, pp. 612–636.

[EC 2.3.1.41 created 1972, modified 2006]