|Gene:||lipA||Accession Numbers: EG11306 (MetaCyc), b0628, ECK0621|
Species: Escherichia coli K-12 substr. MG1655
Subunit composition of
lipoate synthase = [LipA]2
lipoate synthase monomer = LipA
LipA is required for the step of lipoate biosynthesis at which sulfur is inserted into the octanoyl side-chain of an octanoylated E2 domain, to form the lipoate moiety [Reed93, Miller00]. Lipoate is an important cofactor of several important enzyme complexes, such as pyruvate dehydrogenase [Herbert75, Stepp81, Reed93], alpha-ketoglutarate dehydrogenase [Herbert75, Stepp81, Reed93], and the glycine cleavage system [Vanden91, Reed93].
Lipoate synthase is a LipA homodimer with two (4Fe-4S) iron-sulfur clusters per protein dimer under anaerobic conditions, and these clusters are oxidized to the (2Fe-2S) state in air [OllagnierDe00, Ollagnierde99]. This arrangement of dimer interface-spanning, oxygen-sensitive iron-sulfur clusters is characteristic of S-adenosylmethionine-utilizing enzymes that exhibit a radical-mediated cleavage mechanism [Duin97]. The catalytic mechanisms of deoxyadenosine radical iron-sulfur enzymes are presented [Frey01]. The enzyme uses octanoyl side chains (but not free octanoate) as substrate and also uses S-adenosyl methionine [Miller00]. Enzyme activity has been observed in vitro [Miller00].
The lip-2 and lip-9 mutations, which cause lipoic acid auxotrophy, are lipA alleles [Vanden91]; lip-2 encodes an S307F change and lip-9 encodes an E195K change [Hayden93]. Allele-specific effects on lipoic acid biosynthesis (at the sulfur insertion step) have been observed [Hayden93]. The lipoic acid auxotrophy of a lipA mutant is rescued by 6-thiooctanoic acid or 8-thiooctanoic acid [Reed93]. LipA and LipB are also necessary for anaerobic glycine cleavage system activity [Reed93]. The lipoic acid auxotrophy of a lipA mutant is enhanced by an slr-1 (selenolipoic acid-resistant) mutation [Reed94] and complemented by an slr-7 mutation [Reed94], which is a lip duplication [Jordan02].
The site of translation initiation has been determined [Reed93].
Regulation has been described [Inoue02].
|Map Position: [658,474 <- 659,439]|
Molecular Weight of Polypeptide: 36.072 kD (from nucleotide sequence), 36 kD (experimental)
Unification Links: ASAP:ABE-0002155 , CGSC:31534 , DIP:DIP-48008N , EchoBASE:EB1283 , EcoGene:EG11306 , EcoliWiki:b0628 , Mint:MINT-1310776 , ModBase:P60716 , OU-Microarray:b0628 , PortEco:lipA , PR:PRO_000023092 , Pride:P60716 , Protein Model Portal:P60716 , RefSeq:NP_415161 , RegulonDB:EG11306 , String:511145.b0628 , UniProt:P60716
Relationship Links: InterPro:IN-FAMILY:IPR003698 , InterPro:IN-FAMILY:IPR006638 , InterPro:IN-FAMILY:IPR007197 , InterPro:IN-FAMILY:IPR013785 , Panther:IN-FAMILY:PTHR10949 , Pfam:IN-FAMILY:PF04055 , Smart:IN-FAMILY:SM00729
|Biological Process:||GO:0009107 - lipoate biosynthetic process
[GOA06, GOA01, Reed93]
GO:0009249 - protein lipoylation [GOA06, Cicchillo04]
GO:0055114 - oxidation-reduction process [Reed93]
|Molecular Function:||GO:0003826 - alpha-ketoacid dehydrogenase activity
GO:0016992 - lipoate synthase activity [GOA06, GOA01a, GOA01, Cicchillo04]
GO:0051539 - 4 iron, 4 sulfur cluster binding [UniProtGOA11a, GOA06, GOA01, OllagnierDe00]
GO:0003824 - catalytic activity [GOA01]
GO:0016740 - transferase activity [UniProtGOA11a]
GO:0046872 - metal ion binding [UniProtGOA11a]
GO:0051536 - iron-sulfur cluster binding [UniProtGOA11a, GOA01]
|Cellular Component:||GO:0005737 - cytoplasm
[UniProtGOA11, UniProtGOA11a, GOA06, Cicchillo04]
GO:0005829 - cytosol [DiazMejia09, Ishihama08]
|MultiFun Terms:||metabolism → biosynthesis of building blocks → cofactors, small molecule carriers → lipoate|
Enzymatic reaction of: lipoate synthase
Synonyms: lipoic acid synthase
EC Number: 126.96.36.199
a [lipoyl-carrier protein] N6-octanoyl-L-lysine + 2 S-adenosyl-L-methionine + 2 a sulfurated [sulfur carrier] <=> a [lipoyl-carrier protein] N6-lipoyl-L-lysine + 2 5'-deoxyadenosine + 2 L-methionine + 2 an unsulfurated [sulfur carrier]
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the direction shown.
|Mutagenesis-Variant||68 -> 79|
|Mutagenesis-Variant||94 -> 101|
10/20/97 Gene b0628 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG11306; confirmed by SwissProt match.
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
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
Cicchillo04a: Cicchillo RM, Lee KH, Baleanu-Gogonea C, Nesbitt NM, Krebs C, Booker SJ (2004). "Escherichia coli lipoyl synthase binds two distinct [4Fe-4S] clusters per polypeptide." Biochemistry 43(37);11770-81. PMID: 15362861
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
Hayden92: Hayden MA, Huang I, Bussiere DE, Ashley GW (1992). "The biosynthesis of lipoic acid. Cloning of lip, a lipoate biosynthetic locus of Escherichia coli." J Biol Chem 267(14);9512-5. PMID: 1577793
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
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
OllagnierDe00: Ollagnier-De Choudens S, Sanakis Y, Hewitson KS, Roach P, Baldwin JE, Munck E, Fontecave M (2000). "Iron-sulfur center of biotin synthase and lipoate synthase." Biochemistry 39(14);4165-73. PMID: 10747808
Reed94: Reed KE, Morris TW, Cronan JE (1994). "Mutants of Escherichia coli K-12 that are resistant to a selenium analog of lipoic acid identify unknown genes in lipoate metabolism." Proc Natl Acad Sci U S A 91(9);3720-4. PMID: 8170976
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
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