If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Fatty Acid and Lipid Biosynthesis → Fatty Acid Biosynthesis|
Some taxa known to possess this pathway include : Escherichia coli K-12 substr. MG1655
Expected Taxonomic Range: Bacteria
This superpathway starts with the initiation of fatty acids biosynthesis by generating an acetoacetyl-[acp] from acetyl-CoA, hydrogen carbonate and a holo-[acyl-carrier protein] protein. The product, acetoacetyl-[acp], feeds into the pathway of fatty acids elongation, which involves repetition of the same four enzymatic reactions. Each repetition constitutes one turn of a cycle that lengthens the chain of an acyl-[acp] molecule by two carbons. The products of multiple turns of this cycle are drawn off to become components of fatty acid-containing compounds such as phospholipids, lipid A, and lipoproteins. Such products include the saturated fatty acids laurate, myristate, and palmitate [Marr62].
E. coli also contains unsaturated fatty acids, namely palmitoleate and cis-vaccenate. These are formed by a pathway that branches off at the level of the 10-carbon intermediate [Cronan03, Magnuson93]. Once the 10-carbon unsaturated acyl-[acp] is formed, it is elongated by the same cycle.
Of the four reactions involved in the cycle of fatty-acid elongation, two are catalyzed by more that one enzyme. These function preferentially on substrates of different chain length. They also act differentially on saturated and unsaturated substrates [Heath96]. The first reaction in the sequence, the condensation reaction, is catalyzed by three enzymes, FabB, FabF, and FabH. FabH initiates fatty-acid synthesis: it uses only acetyl-ACP as a substrate (see Pathway: fatty acid biosynthesis initiation I) [Lai03]. Only FabB catalyzes the extension of a cis-Δ3-decenoyl-[acp] to a palmitoleoyl-[acp], and only FabF can catalyze the elongation of the later to cis-vaccenate [Campbell01]. The activity of FabF and hence the fraction of fatty acids that are unsaturated is modultated by temperature [Marr62]. Thus the distribution of the flow of synthesis that proceeds to saturated vs. unsaturated fatty acids is determined by the activities of FabA, FabB and growth temperature [Heath96].
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
AbdelHamid07: Abdel-Hamid AM, Cronan JE (2007). "Coordinate expression of the acetyl coenzyme A carboxylase genes, accB and accC, is necessary for normal regulation of biotin synthesis in Escherichia coli." J Bacteriol 189(2);369-76. PMID: 17056747
Alhamadsheh07: Alhamadsheh MM, Musayev F, Komissarov AA, Sachdeva S, Wright HT, Scarsdale N, Florova G, Reynolds KA (2007). "Alkyl-CoA disulfides as inhibitors and mechanistic probes for FabH enzymes." Chem Biol 14(5);513-24. PMID: 17524982
Alhamadsheh08: Alhamadsheh MM, Waters NC, Sachdeva S, Lee P, Reynolds KA (2008). "Synthesis and biological evaluation of novel sulfonyl-naphthalene-1,4-diols as FabH inhibitors." Bioorg Med Chem Lett 18(24);6402-5. PMID: 18996691
Annand93: Annand RR, Kozlowski JF, Davisson V J, Schwab JM (1993). "Mechanism-based inactivation of Escherichia coli .beta.-hydroxydecanoyl thiol ester dehydrase: assignment of the imidazole nitrogen-15 NMR resonances and determination of the structure of the alkylated histidine." Journal of the American Chemical Society 115(3);1088-1094.
Arifuzzaman06: Arifuzzaman M, Maeda M, Itoh A, Nishikata K, Takita C, Saito R, Ara T, Nakahigashi K, Huang HC, Hirai A, Tsuzuki K, Nakamura S, Altaf-Ul-Amin M, Oshima T, Baba T, Yamamoto N, Kawamura T, Ioka-Nakamichi T, Kitagawa M, Tomita M, Kanaya S, Wada C, Mori H (2006). "Large-scale identification of protein-protein interaction of Escherichia coli K-12." Genome Res 16(5);686-91. PMID: 16606699
Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554
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
Barnes68: Barnes EM, Wakil SJ (1968). "Studies on the mechanism of fatty acid synthesis. XIX. Preparation and general properties of palmityl thioesterase." J Biol Chem 1968;243(11);2955-62. PMID: 4871199
Benson08: Benson BK, Meades G, Grove A, Waldrop GL (2008). "DNA inhibits catalysis by the carboxyltransferase subunit of acetyl-CoA carboxylase: implications for active site communication." Protein Sci 17(1);34-42. PMID: 18156466
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
Bilder06: Bilder P, Lightle S, Bainbridge G, Ohren J, Finzel B, Sun F, Holley S, Al-Kassim L, Spessard C, Melnick M, Newcomer M, Waldrop GL (2006). "The structure of the carboxyltransferase component of acetyl-coA carboxylase reveals a zinc-binding motif unique to the bacterial enzyme." Biochemistry 45(6);1712-22. PMID: 16460018
Blanchard99: Blanchard CZ, Chapman-Smith A, Wallace JC, Waldrop GL (1999). "The biotin domain peptide from the biotin carboxyl carrier protein of Escherichia coli acetyl-CoA carboxylase causes a marked increase in the catalytic efficiency of biotin carboxylase and carboxyltransferase relative to free biotin." J Biol Chem 1999;274(45);31767-9. PMID: 10542197
Bognar87: Bognar AL, Osborne C, Shane B (1987). "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 262(25);12337-43. PMID: 3040739
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