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Escherichia coli K-12 substr. MG1655 Pathway: palmitate biosynthesis II (bacteria and plants)
Traceable author statement to experimental support

Pathway diagram: palmitate biosynthesis II (bacteria and plants)

If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Locations of Mapped Genes:

Schematic showing all replicons, marked with selected genes

Genetic Regulation Schematic

Genetic regulation schematic for palmitate biosynthesis II (bacteria and plants)

Synonyms: palmitic acid biosynthesis, de novo lipogenesis

Superclasses: BiosynthesisFatty Acid and Lipid BiosynthesisFatty Acid BiosynthesisPalmitate Biosynthesis

General Background

Fatty acids are key building blocks for the phospholipid components of cell membranes. Palmitate is one of the most common saturated fatty acids found in microorganisms, plants and animals. It was discovered by Edmond Fremy in 1840 in saponified palm oil, of which it is a major component, and hence its name.

Palmitate is synthesized by stepwise condensation of C2 units to a growing acyl chain. Each elongation cycle results in the addition of two carbons to the acyl chain, and consists of four separate reactions. The first step is the condensation of a C2 unit with the nascent [acyl carrier protein]-bound acyl (acyl-[acp]) forming a a 3-oxoacyl-[acp] and CO2. This step is followed by reduction to a (3R)-3-hydroxyacyl-[acyl-carrier protein], dehydration to a trans-2-enoyl-[acyl-carrier protein], and a final reduction to form the elongated fatty acyl-[acp]. This chain of event repeats itself several times, until the final product, a palmitoyl-[acp], is formed.

There are two basic types of fatty acid biosynthesis systems, named type I and type II. The type I system is found in animals and lower eukaryotes (see pathway palmitate biosynthesis I (animals and fungi)). The mammalian system consists of a single gene product that contains all of the reaction centers required to produce a fatty acid, while the system of lower eukaryotes (such as yeast) consists of two genes, whose polypeptide products combine to form a multifunctional complex.

The type II systems are found in bacteria and plants [White05], parasites of the Apicomplexa phylum [Ferguson07], and mitochondria [Zhang03, Miinalainen03]. The reactions in these systems are catalyzed by a series of individual soluble proteins that are each encoded by a discrete gene, and the pathway intermediates are transferred between the enzymes as thioesters of a holo-[acyl-carrier protein].

Unlike the type I system that accepts malonyl-CoA as the source of the two-carbon units, the type II systems accept only a malonyl-[acp]. In E. coli the final product of this pathway is a palmitoyl-[acp]. In some bacteria and plants, but not E. coli, the acyl moiety is released from the [acyl carrier protein] by an acyl-[acyl-carrier-protein] hydrolase (EC or EC [Jeon11, Pollard91].

About This Pathway

This pathway is an instance of the generalized fatty acid elongation pathway depicted in fatty acid elongation -- saturated. It shows the elongation of an acetoacetyl-[acp] produced by the fatty acid biosynthesis initiation reactions (shown in superpathway of fatty acid biosynthesis initiation (E. coli)) to produce a palmitoyl-[acp].

As noted above, the final product of the E. coli pathway is a palmitoyl-[acp]. E. coli lacks an acyl-[acyl-carrier-protein] hydrolase (EC that releases palmitate from a palmitoyl-[acp]. Instead, the acyl chain of a palmitoyl-[acp] is transferred into membrane phospholipids by a sn-glycerol 3-phosphate acyltransferase system (see pathway CDP-diacylglycerol biosynthesis II).

Reviews: [White05, Chan10a], and Cronan, J.E. Jr., and C.O. Rock (2008) "Biosynthesis of Membrane Lipids" EcoSal 3.6.4 [ECOSAL]

Created 10-Jul-2008 by Caspi R, SRI International
Last-Curated 15-Apr-2013 by Fulcher C, SRI International


Chan10a: Chan DI, Vogel HJ (2010). "Current understanding of fatty acid biosynthesis and the acyl carrier protein." Biochem J 430(1);1-19. PMID: 20662770

ECOSAL: "Escherichia coli and Salmonella: Cellular and Molecular Biology." Online edition.

Ferguson07: Ferguson DJ, Campbell SA, Henriquez FL, Phan L, Mui E, Richards TA, Muench SP, Allary M, Lu JZ, Prigge ST, Tomley F, Shirley MW, Rice DW, McLeod R, Roberts CW (2007). "Enzymes of type II fatty acid synthesis and apicoplast differentiation and division in Eimeria tenella." Int J Parasitol 37(1);33-51. PMID: 17112527

Jeon11: Jeon E, Lee S, Won JI, Han SO, Kim J, Lee J (2011). "Development of Escherichia coli MG1655 strains to produce long chain fatty acids by engineering fatty acid synthesis (FAS) metabolism." Enzyme Microb Technol 49(1);44-51. PMID: 22112270

Miinalainen03: Miinalainen IJ, Chen ZJ, Torkko JM, Pirila PL, Sormunen RT, Bergmann U, Qin YM, Hiltunen JK (2003). "Characterization of 2-enoyl thioester reductase from mammals. An ortholog of YBR026p/MRF1'p of the yeast mitochondrial fatty acid synthesis type II." J Biol Chem 278(22);20154-61. PMID: 12654921

Pollard91: Pollard MR, Anderson L, Fan C, Hawkins DJ, Davies HM (1991). "A specific acyl-ACP thioesterase implicated in medium-chain fatty acid production in immature cotyledons of Umbellularia californica." Arch Biochem Biophys 284(2);306-12. PMID: 1989513

White05: White SW, Zheng J, Zhang YM, Rock (2005). "The structural biology of type II fatty acid biosynthesis." Annu Rev Biochem 74;791-831. PMID: 15952903

Zhang03: Zhang L, Joshi AK, Smith S (2003). "Cloning, expression, characterization, and interaction of two components of a human mitochondrial fatty acid synthase. Malonyltransferase and acyl carrier protein." J Biol Chem 278(41);40067-74. PMID: 12882974

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Baldock96: Baldock C, Rafferty JB, Sedelnikova SE, Baker PJ, Stuitje AR, Slabas AR, Hawkes TR, Rice DW (1996). "A mechanism of drug action revealed by structural studies of enoyl reductase." Science 274(5295);2107-10. PMID: 8953047

Bergler92: Bergler H, Hogenauer G, Turnowsky F (1992). "Sequences of the envM gene and of two mutated alleles in Escherichia coli." J Gen Microbiol 1992;138 ( Pt 10);2093-100. PMID: 1364817

Bergler94: Bergler H, Wallner P, Ebeling A, Leitinger B, Fuchsbichler S, Aschauer H, Kollenz G, Hogenauer G, Turnowsky F (1994). "Protein EnvM is the NADH-dependent enoyl-ACP reductase (FabI) of Escherichia coli." J Biol Chem 1994;269(8);5493-6. PMID: 8119879

Bergler96: Bergler H, Fuchsbichler S, Hogenauer G, Turnowsky F (1996). "The enoyl-[acyl-carrier-protein] reductase (FabI) of Escherichia coli, which catalyzes a key regulatory step in fatty acid biosynthesis, accepts NADH and NADPH as cofactors and is inhibited by palmitoyl-CoA." Eur J Biochem 242(3);689-94. PMID: 9022698

Borgaro11: Borgaro JG, Chang A, Machutta CA, Zhang X, Tonge PJ (2011). "Substrate recognition by β-ketoacyl-ACP synthases." Biochemistry 50(49);10678-86. PMID: 22017312

Byers07: Byers DM, Gong H (2007). "Acyl carrier protein: structure-function relationships in a conserved multifunctional protein family." Biochem Cell Biol 85(6);649-62. PMID: 18059524

Campbell01a: Campbell JW, Cronan JE (2001). "Bacterial fatty acid biosynthesis: targets for antibacterial drug discovery." Annu Rev Microbiol 55;305-32. PMID: 11544358

Cao10: Cao Y, Yang J, Xian M, Xu X, Liu W (2010). "Increasing unsaturated fatty acid contents in Escherichia coli by coexpression of three different genes." Appl Microbiol Biotechnol 87(1);271-80. PMID: 20135119

DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114

Escaich11: Escaich S, Prouvensier L, Saccomani M, Durant L, Oxoby M, Gerusz V, Moreau F, Vongsouthi V, Maher K, Morrissey I, Soulama-Mouze C (2011). "The MUT056399 inhibitor of FabI is a new antistaphylococcal compound." Antimicrob Agents Chemother 55(10);4692-7. PMID: 21825292

Feng09: Feng Y, Cronan JE (2009). "Escherichia coli unsaturated fatty acid synthesis: complex transcription of the fabA gene and in vivo identification of the essential reaction catalyzed by FabB." J Biol Chem 284(43);29526-35. PMID: 19679654

Garwin80: Garwin JL, Klages AL, Cronan JE (1980). "Structural, enzymatic, and genetic studies of beta-ketoacyl-acyl carrier protein synthases I and II of Escherichia coli." J Biol Chem 1980;255(24);11949-56. PMID: 7002930

GOA01: GOA, MGI (2001). "Gene Ontology annotation based on Enzyme Commission mapping." Genomics 74;121-128.

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

GOA06: GOA, SIB (2006). "Electronic Gene Ontology annotations created by transferring manual GO annotations between orthologous microbial proteins."

Goh09: Goh S, Boberek JM, Nakashima N, Stach J, Good L (2009). "Concurrent growth rate and transcript analyses reveal essential gene stringency in Escherichia coli." PLoS One 4(6);e6061. PMID: 19557168

Heath01: Heath RJ, White SW, Rock CO (2001). "Lipid biosynthesis as a target for antibacterial agents." Prog Lipid Res 40(6);467-97. PMID: 11591436

Heath95: Heath RJ, Rock CO (1995). "Enoyl-acyl carrier protein reductase (fabI) plays a determinant role in completing cycles of fatty acid elongation in Escherichia coli." J Biol Chem 270(44);26538-42. PMID: 7592873

Heath96: Heath RJ, Rock CO (1996). "Roles of the FabA and FabZ beta-hydroxyacyl-acyl carrier protein dehydratases in Escherichia coli fatty acid biosynthesis." J Biol Chem 1996;271(44);27795-801. PMID: 8910376

Heath96a: Heath RJ, Rock CO (1996). "Regulation of fatty acid elongation and initiation by acyl-acyl carrier protein in Escherichia coli." J Biol Chem 1996;271(4);1833-6. PMID: 8567624

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Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
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