Metabolic Modeling Tutorial
registration ends
Sat Mar 7th, 2015
Metabolic Modeling Tutorial
registration ends
Sat Mar 7th, 2015
Metabolic Modeling Tutorial
registration ends
Sat Mar 7th, 2015
Metabolic Modeling Tutorial
registration ends
Sat Mar 7th, 2015
Metabolic Modeling Tutorial
registration ends
Sat Mar 7th, 2015

MetaCyc Pathway: lipoate biosynthesis and incorporation I

This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Superclasses: Biosynthesis Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis Lipoate Biosynthesis

Some taxa known to possess this pathway include ? : Escherichia coli K-12 substr. MG1655

Expected Taxonomic Range: Bacteria , Eukaryota , Viridiplantae

General Background

Lipoate is an organosulfur compound that contains a ditholane ring, which is a cyclic disulfide. Lipoate is used as an essential cofactor by many enzyme complexes involved in oxidative metabolism, including the pyruvate dehydrogenase complex [Herbert75, Stepp81, Reed93], the 2-oxoglutarate decarboxylation to succinyl-CoA [Herbert75, Stepp81, Reed93], the 2-oxoisovalerate decarboxylation to isobutanoyl-CoA [Reed90], and the glycine cleavage [Vanden91, Reed93].

Each of these enzyme complexes is composed of multiple copies of three enzymes: a substrate-specific decarboxylase-dehydrogenase (E1), a dihydrolipoamide acyltransferase (E2) specific for each type of complex, and a dihydrolipoamide dehydrogenase (E3). The (E2) proteins have a dedicated lipoyl domain. In order for the complex to be active, lipoate must be attached to the lipoyl domain by an amide linkage between its carboxylate moiety and a specific lysine residue in the enzyme [Reed93]..

E1 catalyzes a reaction in which the substrate is attached to the lipoate cofactor and decarboxylated. During this reaction, the lipoate cofactor is reduced to dihydriolipoate. E2 then catalyzes an acyl transfer step, in which the product of the reaction is released. Finally, E3 catalyzes the oxidation of the dihydrolipoyl cofactor back to lipoyl form, with NAD being the ultimate electron acceptor [Reed90].

About This Pathway

The biosynthesis of lipoate is unusual, and shares the same mechanism as the biosynthesis of biotin. The precursor octanoate molecule is first attached to a specific L-lysine residue within the lipoyl domain, and is then converted to lipoate.

The first enzyme in this pathway, lipoyl(octanoyl) transferase, transfers the octanoate moiety from octanoate-[acp] molecule to a specific lysyl residue in lipoate-dependent enzymes, resulting in a [lipoyl-carrier protein] N6-octanoyl-L-lysine, and regenerating the acyl-carrier protein in the process [Morris95, Zhao03b]. lipoyl(octanoyl) transferase-mediated attachment of octanoate to the apo-domain probably does not occur unless the octanoate is bound to an acyl-carrier protein.

The next enzyme in the pathway, lipoate synthase, catalyzes the conversion of the octanoyl side chain to an active lipoyl, generating a fully active lipoylated domain. The enzyme is an iron-sulfur protein that requires the presence of the cofactor pyridoxal phosphate (PLP), and the molecule S-adenosyl-L-methionine (AdoMet) [Reed93, Miller00]. An electron which originates from the [4Fe-4S] cluster of the enzyme serves to split at least two molecules of AdoMet into a 5'-deoxyadenosyl radical and methionine [Ollagnierde02]. The radical then abstracts a hydrogen from a C-H bond of thew octanoyl side chain, becoming 5'-adenosine in the process. The newly-formed unstable octanoyl radical then reacts directly with the Fe-S center of the enzyme. Two sulfur atoms from the center enter the structure of the octanoyl side chain, producing lipoyl, which dissociates from the enzyme along with excess iron, leaving it with a [2Fe-2S] center. Thus, in this unusual reaction, the iron-sulfur center of the enzyme is not just a catalytic accelerator, but also a substrate, donating the two sulfur atoms [Marquet01]. It should be noted that although this process has been well documented in vitro [Miller00], there is still a possibility that there exists another sulfur donor in vivo, and that the Fe-S center acts as sulfur donor only in the absence of this natural donor [Frey01].

It has been suggested that the conversion of octanoylated-domains to lipoylated ones described in this pathway may be a type of a repair pathway, activated only if the other lipoate biosynthetic pathways are malfunctioning [Zhao03b].

Other routes for lipoate incorporation involve the lipoyl-protein ligase LplA, which utilizes either lipoate or octanoate imported from outside the cell (see lipoate salvage I and lipoate biosynthesis and incorporation II).

Lipoate Biosynthesis in Other Organisms

Genes encoding LipA and LipB have been identified in mammalian genomes and it has been shown that mammalian cells are capable of synthesizing (R)-lipoate in mitochondria [Morikawa01]. However, their significance is not fully understood because it is generally believed that mammals primarily rely on salvaged (R)-lipoate (see lipoate salvage I). Lipoate biosynthesis has also been demonstrated in plants [Gueguen00].

It is not clear whether Archaea utilize lipoate. No clear evidence is available, although the genes encoding a putative 2-oxoacid dehydrogenase complex have been reported in Haloferax volcanii [Jolley00].

Variants: lipoate biosynthesis and incorporation (glycine cleavage system, yeast) , lipoate biosynthesis and incorporation (pyruvate dehydrogenase and oxoglutarate dehydrogenase, yeast) , lipoate biosynthesis and incorporation II , lipoate biosynthesis and incorporation III (Bacillus) , lipoate salvage I , lipoate salvage II

Unification Links: EcoCyc:PWY0-501

Created 26-Mar-2003 by Arnaud M , SRI International
Revised 08-May-2006 by Caspi R , SRI International


Frey01: Frey PA (2001). "Radical mechanisms of enzymatic catalysis." Annu Rev Biochem 70;121-48. PMID: 11395404

Gueguen00: Gueguen V, Macherel D, Jaquinod M, Douce R, Bourguignon J (2000). "Fatty acid and lipoic acid biosynthesis in higher plant mitochondria." J Biol Chem 275(7);5016-25. PMID: 10671542

Herbert75: Herbert AA, Guest JR (1975). "Lipoic acid content of Escherichia coli and other microorganisms." Arch Microbiol 106(3);259-66. PMID: 814874

Jolley00: Jolley KA, Maddocks DG, Gyles SL, Mullan Z, Tang SL, Dyall-Smith ML, Hough DW, Danson MJ (2000). "2-Oxoacid dehydrogenase multienzyme complexes in the halophilic Archaea? Gene sequences and protein structural predictions." Microbiology 146 ( Pt 5);1061-9. PMID: 10832633

Marquet01: Marquet A, Bui BT, Florentin D (2001). "Biosynthesis of biotin and lipoic acid." Vitam Horm 61;51-101. PMID: 11153271

Miller00: Miller JR, Busby RW, Jordan SW, Cheek J, Henshaw TF, Ashley GW, Broderick JB, Cronan JE, Marletta MA (2000). "Escherichia coli LipA is a lipoyl synthase: in vitro biosynthesis of lipoylated pyruvate dehydrogenase complex from octanoyl-acyl carrier protein." Biochemistry 39(49);15166-78. PMID: 11106496

Morikawa01: Morikawa T, Yasuno R, Wada H (2001). "Do mammalian cells synthesize lipoic acid? Identification of a mouse cDNA encoding a lipoic acid synthase located in mitochondria." FEBS Lett 498(1);16-21. PMID: 11389890

Morris95: Morris TW, Reed KE, Cronan JE (1995). "Lipoic acid metabolism in Escherichia coli: the lplA and lipB genes define redundant pathways for ligation of lipoyl groups to apoprotein." J Bacteriol 177(1);1-10. PMID: 8002607

Ollagnierde02: Ollagnier-de Choudens S, Sanakis Y, Hewitson KS, Roach P, Munck E, Fontecave M (2002). "Reductive cleavage of S-adenosylmethionine by biotin synthase from Escherichia coli." J Biol Chem 277(16);13449-54. PMID: 11834738

Reed90: Reed LJ, Hackert ML (1990). "Structure-function relationships in dihydrolipoamide acyltransferases." J Biol Chem 265(16);8971-4. PMID: 2188967

Reed93: Reed KE, Cronan JE (1993). "Lipoic acid metabolism in Escherichia coli: sequencing and functional characterization of the lipA and lipB genes." J Bacteriol 175(5);1325-36. PMID: 8444795

Stepp81: Stepp LR, Bleile DM, McRorie DK, Pettit FH, Reed LJ (1981). "Use of trypsin and lipoamidase to study the role of lipoic acid moieties in the pyruvate and alpha-ketoglutarate dehydrogenase complexes of Escherichia coli." Biochemistry 20(16);4555-60. PMID: 6794598

Vanden91: Vanden Boom TJ, Reed KE, Cronan JE (1991). "Lipoic acid metabolism in Escherichia coli: isolation of null mutants defective in lipoic acid biosynthesis, molecular cloning and characterization of the E. coli lip locus, and identification of the lipoylated protein of the glycine cleavage system." J Bacteriol 173(20);6411-20. PMID: 1655709

Zhao03b: Zhao X, Miller JR, Jiang Y, Marletta MA, Cronan JE (2003). "Assembly of the covalent linkage between lipoic acid and its cognate enzymes." Chem Biol 10(12);1293-302. PMID: 14700636

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

Booker07: Booker SJ, Cicchillo RM, Grove TL (2007). "Self-sacrifice in radical S-adenosylmethionine proteins." Curr Opin Chem Biol 11(5);543-52. PMID: 17936058

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

Chang91: Chang YY, Cronan JE, Li SJ, Reed K, Vanden Boom T, Wang AY (1991). "Locations of the lip, poxB, and ilvBN genes on the physical map of Escherichia coli." J Bacteriol 173(17);5258-9. PMID: 1832150

Chen97a: Chen XJ (1997). "Cloning and characterization of the lipoyl-protein ligase gene LIPB from the yeast Kluyveromyces lactis: synergistic respiratory deficiency due to mutations in LIPB and mitochondrial F1-ATPase subunits." Mol Gen Genet 255(3);341-9. PMID: 9268025

Cicchillo04: Cicchillo RM, Iwig DF, Jones AD, Nesbitt NM, Baleanu-Gogonea C, Souder MG, Tu L, Booker SJ (2004). "Lipoyl synthase requires two equivalents of S-adenosyl-L-methionine to synthesize one equivalent of lipoic acid." Biochemistry 43(21);6378-86. PMID: 15157071

Creaghan78: Creaghan IT, Guest JR (1978). "Succinate dehydrogenase-dependent nutritional requirement for succinate in mutants of Escherichia coli K12." J Gen Microbiol 107(1);1-13. PMID: 366070

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

Duin97: Duin EC, Lafferty ME, Crouse BR, Allen RM, Sanyal I, Flint DH, Johnson MK (1997). "[2Fe-2S] to [4Fe-4S] cluster conversion in Escherichia coli biotin synthase." Biochemistry 36(39);11811-20. PMID: 9305972

GOA01: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

GOA01a: GOA, MGI (2001). "Gene Ontology annotation based on Enzyme Commission mapping." Genomics 74;121-128.

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

Hayden93: Hayden MA, Huang IY, Iliopoulos G, Orozco M, Ashley GW (1993). "Biosynthesis of lipoic acid: characterization of the lipoic acid auxotrophs Escherichia coli W1485-lip2 and JRG33-lip9." Biochemistry 32(14);3778-82. PMID: 8466915

Herbert68: Herbert AA, Guest JR (1968). "Biochemical and genetic studies with lysine+methionine mutants of Escherichia coli: lipoic acid and alpha-ketoglutarate dehydrogenase-less mutants." J Gen Microbiol 53(3);363-81. PMID: 4889470

Inoue02: Inoue K, Chen J, Kato I, Inouye M (2002). "Specific growth inhibition by acetate of an Escherichia coli strain expressing Era-dE, a dominant negative Era mutant." J Mol Microbiol Biotechnol 4(4);379-88. PMID: 12125819

Ishihama08: Ishihama Y, Schmidt T, Rappsilber J, Mann M, Hartl FU, Kerner MJ, Frishman D (2008). "Protein abundance profiling of the Escherichia coli cytosol." BMC Genomics 9;102. PMID: 18304323

Jordan02: Jordan SW, Cronan JE (2002). "Chromosomal amplification of the Escherichia coli lipB region confers high-level resistance to selenolipoic acid." J Bacteriol 184(19);5495-501. PMID: 12218038

Jordan03: Jordan SW, Cronan JE (2003). "The Escherichia coli lipB gene encodes lipoyl (octanoyl)-acyl carrier protein:protein transferase." J Bacteriol 185(5);1582-9. PMID: 12591875

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Martin09: Martin N, Lombardia E, Altabe SG, de Mendoza D, Mansilla MC (2009). "A lipA (yutB) mutant, encoding lipoic acid synthase, provides insight into the interplay between branched-chain and unsaturated fatty acid biosynthesis in Bacillus subtilis." J Bacteriol 191(24);7447-55. PMID: 19820084

Nesbitt05: Nesbitt NM, Baleanu-Gogonea C, Cicchillo RM, Goodson K, Iwig DF, Broadwater JA, Haas JA, Fox BG, Booker SJ (2005). "Expression, purification, and physical characterization of Escherichia coli lipoyl(octanoyl)transferase." Protein Expr Purif 39(2);269-82. PMID: 15642479

Showing only 20 references. To show more, press the button "Show all references".

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Fri Mar 6, 2015, BIOCYC13A.