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Pathway Description
Palmitate Biosynthesis 2
actinobacillus succinogenes 130Z
Category:
Metabolite Pathway
Sub-Category:
Metabolic
Created: 2025-03-17
Last Updated: 2025-06-26
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 pathway starts with acetyl-CoA interacting with hydrogen carbonate through an ATP driven acetyl-CoA carboxylase resulting in a phosphate, an ADP , a hydrogen ion and a malonyl-CoA. The latter compound interacts with a holo-[acp] through a malonyl-CoA-ACP transacylase resulting in a CoA and a malonyl-[acp]. This compound interacts with hydrogen ion, acetyl-CoA through a KASIII resulting in a CoA, carbon dioxide and an acetoacetyl-[acp]. The latter compound interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (R) 3-Hydroxybutanoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a crotonyl-[acp](2). The crotonyl-[acp] interacts with a hydrogen ion through a NADH enoyl-[acyl-carrier-protein] reductase(NAD) resulting in NAD and a butyryl-[acp](3). The butyryl-[acp] interacts with a hydrogen ion, a malonyl-[acp] through a KASI resulting in a holo-[acp],carbon dioxide and a 3-oxo-hexanoyl-[acp](4). The 3-oxo-hexanoyl-[acp] interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (R) 3-Hydroxyhexanoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a trans hex-2-enoyl-[acp](2). The trans hex-2-enoyl-[acp] interacts with a hydrogen ion through a NADH enoyl-[acyl-carrier-protein] reductase(NAD) resulting in NAD and a hexanoyl-[acp](3). The hexanoyl-[acp] interacts with a hydrogen ion, a malonyl-[acp] through a KASI resulting in a holo-[acp],carbon dioxide and a 3-oxo-octanoyl-[acp](4). The 3-oxo-octanoyl-[acp] interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (R) 3-Hydroxyoctanoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a trans oct-2-enoyl-[acp](2). The trans oct-2-enoyl-[acp] interacts with a hydrogen ion through a NADH enoyl-[acyl-carrier-protein] reductase(NAD) resulting in NAD and a octanoyl-[acp](3). The octanoyl-[acp] interacts with a hydrogen ion, a malonyl-[acp] through a KASI resulting in a holo-[acp],carbon dioxide and a 3-oxo-decanoyl-[acp](4). The 3-oxo-decanoyl-[acp] interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (R) 3-Hydroxydecanoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a trans-delta2-decenoyl-[acp](2). The a trans-delta2-decenoyl-[acp] interacts with a hydrogen ion through a NADH enoyl-[acyl-carrier-protein] reductase(NAD) resulting in NAD and a decanoyl-[acp](3). The decanoyl-[acp] interacts with a malonyl-[acp] through a KASI resulting in a holo-[acp],carbon dioxide and a 3-oxo-dodecanoyl-[acp](4). The 3-oxo-dodecanoyl-[acp ]interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (R) 3-Hydroxydodecanoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a trans dodec-2-enoyl-[acp](2). The trans dodec-2-enoyl-[acp] interacts with a hydrogen ion through a NADH enoyl-[acyl-carrier-protein] reductase(NAD) resulting in NAD and a dodecanoyl-[acp](3). This compound can either react with water spontaneously resulting in a hydrogen ion, a holo-[acp] and a dodecanoic acid or it interacts with a hydrogen ion, a malonyl-[acp] through a KASI resulting in a holo-[acp],carbon dioxide and a 3-oxo-myristoyl-[acp](4). The 3-oxo-myristoyl-[acp] interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (3R) 3-Hydroxymyristoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a trans tetradec-2-enoyl-[acp](2). This compound interacts with a hydrogen ion, through a NADH-driven KASI resulting in a NAD and a myristoyl-[acp]. Myristoyl-[acp] with a hydrogen ion, a malonyl-[acp] through a KASI resulting in a holo-[acp],carbon dioxide and a 3-oxo-palmitoyl-[acp](4). The 3-oxo-palmitoyl-[acp] interacts with a hydrogen ion through a NADPH driven 3-oxoacyl-[acyl-carrier-protein] reductase resulting in an NADP and a (3R) 3-Hydroxypalmitoyl-[acp](1). This compound is then dehydrated by a 3-hydroxyacyl-[acyl-carrier-protein] dehydratase resulting in the release of water and a trans hexadecenoyl-[acp](2). The trans hexadecenoyl-[acp] interacts with a hydrogen ion through a NADH enoyl-[acyl-carrier-protein] reductase(NAD) resulting in NAD and a palmitoyl-[acp](3). Palmitoyl then reacts with water spontaneously resulting in a hydrogen ion, a holo-[acp] and palmitic acid. No integral membrane protein required for long chain fatty acid uptake has been identified in E. coli. The transport of long chain fatty acids across the cytoplasmic membrane is dependent on fatty acyl-CoA synthetase. An energised membrane is necessary for fatty acid transport and it has been suggested that uncharged fatty acids flip across the inner membrane by diffusion.
References
Palmitate Biosynthesis 2 References
Li SJ, Cronan JE Jr: The genes encoding the two carboxyltransferase subunits of Escherichia coli acetyl-CoA carboxylase. J Biol Chem. 1992 Aug 25;267(24):16841-7.
Pubmed: 1355089
Yamamoto Y, Miwa Y, Miyoshi K, Furuyama J, Ohmori H: The Escherichia coli ldcC gene encodes another lysine decarboxylase, probably a constitutive enzyme. Genes Genet Syst. 1997 Jun;72(3):167-72.
Pubmed: 9339543
Blattner FR, Plunkett G 3rd, Bloch CA, Perna NT, Burland V, Riley M, Collado-Vides J, Glasner JD, Rode CK, Mayhew GF, Gregor J, Davis NW, Kirkpatrick HA, Goeden MA, Rose DJ, Mau B, Shao Y: The complete genome sequence of Escherichia coli K-12. Science. 1997 Sep 5;277(5331):1453-62. doi: 10.1126/science.277.5331.1453.
Pubmed: 9278503
Bognar AL, Osborne C, Shane B: Primary structure of the Escherichia coli folC gene and its folylpolyglutamate synthetase-dihydrofolate synthetase product and regulation of expression by an upstream gene. J Biol Chem. 1987 Sep 5;262(25):12337-43.
Pubmed: 3040739
Nonet ML, Marvel CC, Tolan DR: The hisT-purF region of the Escherichia coli K-12 chromosome. Identification of additional genes of the hisT and purF operons. J Biol Chem. 1987 Sep 5;262(25):12209-17.
Pubmed: 3040734
Yamamoto Y, Aiba H, Baba T, Hayashi K, Inada T, Isono K, Itoh T, Kimura S, Kitagawa M, Makino K, Miki T, Mitsuhashi N, Mizobuchi K, Mori H, Nakade S, Nakamura Y, Nashimoto H, Oshima T, Oyama S, Saito N, Sampei G, Satoh Y, Sivasundaram S, Tagami H, Horiuchi T, et al.: Construction of a contiguous 874-kb sequence of the Escherichia coli -K12 genome corresponding to 50.0-68.8 min on the linkage map and analysis of its sequence features. DNA Res. 1997 Apr 28;4(2):91-113. doi: 10.1093/dnares/4.2.91.
Pubmed: 9205837
Kondo H, Shiratsuchi K, Yoshimoto T, Masuda T, Kitazono A, Tsuru D, Anai M, Sekiguchi M, Tanabe T: Acetyl-CoA carboxylase from Escherichia coli: gene organization and nucleotide sequence of the biotin carboxylase subunit. Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9730-3. doi: 10.1073/pnas.88.21.9730.
Pubmed: 1682920
Li SJ, Cronan JE Jr: The gene encoding the biotin carboxylase subunit of Escherichia coli acetyl-CoA carboxylase. J Biol Chem. 1992 Jan 15;267(2):855-63.
Pubmed: 1370469
Muramatsu S, Mizuno T: Nucleotide sequence of the fabE gene and flanking regions containing a bent DNA sequence of Escherichia coli. Nucleic Acids Res. 1989 May 25;17(10):3982. doi: 10.1093/nar/17.10.3982.
Pubmed: 2660106
Alix JH: A rapid procedure for cloning genes from lambda libraries by complementation of E. coli defective mutants: application to the fabE region of the E. coli chromosome. DNA. 1989 Dec;8(10):779-89. doi: 10.1089/dna.1989.8.779.
Pubmed: 2575489
This pathway was propagated using PathWhiz -
Pon, A. et al. Pathways with PathWhiz (2015) Nucleic Acids Res. 43(Web Server issue): W552–W559.
Propagated from SMP0002058
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