IUBMB Enzyme Nomenclature


Accepted name: β-ketoacyl-[acyl-carrier-protein] synthase II

Reaction: a (Z)-hexadec-9-enoyl-[acyl-carrier protein] + a malonyl-[acyl-carrier protein] = a (Z)-3-oxooctadec-11-enoyl-[acyl-carrier protein] + CO2 + an [acyl-carrier protein]

Glossary: palmitoleoyl-[acyl-carrier protein] = (Z)-hexadec-9-enoyl-[acyl-carrier protein]
cis-vaccenoyl-[acyl-carrier protein] = (Z)-octadec-11-enoyl-[acyl-carrier protein]

Other name(s): KASII; KAS II; FabF; 3-oxoacyl-acyl carrier protein synthase II; β-ketoacyl-ACP synthase II

Systematic name: (Z)-hexadec-9-enoyl-[acyl-carrier protein]:malonyl-[acyl-carrier protein] C-acyltransferase (decarboxylating)

Comments: Involved in the dissociated (or type II) fatty acid biosynthesis system that occurs in plants and bacteria. While the substrate specificity of this enzyme is very similar to that of EC, β-ketoacyl-[acyl-carrier-protein] synthase I, it differs in that palmitoleoyl-[acyl-carrier protein] is not a good substrate of EC but is an excellent substrate of this enzyme [1,2]. The fatty-acid composition of Escherichia coli changes as a function of growth temperature, with the proportion of unsaturated fatty acids increasing with lower growth temperature. This enzyme controls the temperature-dependent regulation of fatty-acid composition, with mutants lacking this acivity being deficient in the elongation of palmitoleate to cis-vaccenate at low temperatures [3,4].

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 1048648-42-5


1. 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]

2. 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]

3. Price, A.C., Rock, C.O. and White, S.W. The 1.3-Angstrom-resolution crystal structure of β-ketoacyl-acyl carrier protein synthase II from Streptococcus pneumoniae. J. Bacteriol. 185 (2003) 4136-4143. [PMID: 12837788]

4. Garwin, J.L., Klages, A.L. and Cronan, J.E., Jr. β-Ketoacyl-acyl carrier protein synthase II of Escherichia coli. Evidence for function in the thermal regulation of fatty acid synthesis. J. Biol. Chem. 255 (1980) 3263-3265. [PMID: 6988423]

5. Magnuson, K., Carey, M.R. and Cronan, J.E., Jr. The putative fabJ gene of Escherichia coli fatty acid synthesis is the fabF gene. J. Bacteriol. 177 (1995) 3593-3595. [PMID: 7768872]

6. 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 created 2006, modified 2020]

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