title: Scavenging of cytosolic octanoic acid by mutant LplA lipoate ligases allows growth of Escherichia coli strains lacking the LipB octanoyltransferase of lipoic acid synthesis.
abstract: The LipB octanoyltransferase catalyzes the first step of lipoic acid synthesis in Escherichia coli, transfer of the octanoyl moiety from octanoyl-acyl carrier protein to the lipoyl domains of the E2 subunits of the 2-oxoacid dehydrogenases of aerobic metabolism. Strains containing null mutations in lipB are auxotrophic for either lipoic acid or octanoic acid. We report the isolation of two spontaneously arising mutant strains that allow growth of lipB strains on glucose minimal medium; we determined that suppression was caused by single missense mutations within the coding sequence of the gene (lplA) that encodes lipoate-protein ligase. The LplA proteins encoded by the mutant genes have reduced K(m) values for free octanoic acid and thus are able to scavenge cytosolic octanoic acid for octanoylation of lipoyl domains.
authors.affiliation: Department of Microbiology, University of Illinois, 601 S. Goodwin Ave., Urbana, IL 61801, USA.
authors.forename: Fatemah A M
authors.initials: FA
authors.lastname: Hermes
authors.forename: John E
authors.initials: JE
authors.lastname: Cronan
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000502:physiology*; D015153:Blotting, Western; D002210:Caprylates / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D008025:Ligases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D016296:Mutagenesis; D009154:Mutation; D020125:Mutation, Missense; D016133:Polymerase Chain Reaction; D008063:Thioctic Acid / Q000378:metabolism*
chemical_list: D002210:Caprylates; D029968:Escherichia coli Proteins; C490345:lplA protein, E coli; D008063:Thioctic Acid; D000217:Acyltransferases; C421483:LipB protein, E coli; D008025:Ligases; C031492:octanoic acid
references.citation: J Biol Chem. 2005 Jan 21;280(3):2244-56
references.pmid: 15528186
references.citation: Mol Microbiol. 1996 Jul;21(2):213-9
references.pmid: 8858577
references.citation: J Chromatogr A. 2008 Jul 11;1198-1199:14-20
references.pmid: 18533162
references.citation: Annu Rev Biochem. 2000;69:961-1004
references.pmid: 10966480
references.citation: J Mol Biol. 1985 Oct 20;185(4):743-54
references.pmid: 3903169
references.citation: Proc Natl Acad Sci U S A. 2006 Jun 6;103(23):8662-7
references.pmid: 16735476
references.citation: Adv Microb Physiol. 2005;50:103-46
references.pmid: 16221579
references.citation: J Bacteriol. 2002 Oct;184(19):5495-501
references.pmid: 12218038
references.citation: J Biol Chem. 1994 Jun 10;269(23):16091-100
references.pmid: 8206909
references.citation: J Biol Chem. 2009 Aug 7;284(32):21317-26
references.pmid: 19520844
references.citation: J Bacteriol. 1991 Oct;173(20):6411-20
references.pmid: 1655709
references.citation: J Bacteriol. 1984 Apr;158(1):354-6
references.pmid: 6232260
references.citation: J Biol Chem. 1981 Jan 25;256(2):736-42
references.pmid: 7005223
references.citation: Biochem J. 1995 Aug 1;309 ( Pt 3):853-62
references.pmid: 7639702
references.citation: Microbiol Rev. 1989 Mar;53(1):1-24
references.pmid: 2540407
references.citation: J Mol Biol. 2006 Feb 24;356(3):625-37
references.pmid: 16384580
references.citation: Biochemistry. 2006 Aug 22;45(33):10008-19
references.pmid: 16906759
references.citation: Anal Biochem. 1976 May 7;72:248-54
references.pmid: 942051
references.citation: Proc Natl Acad Sci U S A. 1994 Apr 26;91(9):3720-4
references.pmid: 8170976
references.citation: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
references.pmid: 10829079
references.citation: J Bacteriol. 1995 Jan;177(1):1-10
references.pmid: 8002607
references.citation: Biochemistry. 2005 Dec 20;44(50):16737-46
references.pmid: 16342964
references.citation: J Gen Microbiol. 1968 Oct;53(3):363-81
references.pmid: 4889470
references.citation: J Biol Chem. 2005 Sep 30;280(39):33645-51
references.pmid: 16043486
references.citation: J Biol Chem. 1995 Mar 3;270(9):4216-9
references.pmid: 7876180
references.citation: Chem Biol. 2003 Dec;10(12):1293-302
references.pmid: 14700636
references.citation: Science. 1952 Sep 26;116(3013):329-31
references.pmid: 12984118
references.citation: J Gen Microbiol. 1973 Mar;75(1):197-210
references.pmid: 4578971
references.citation: J Biol Chem. 2005 Nov 11;280(45):38081-9
references.pmid: 16141198
references.citation: J Bacteriol. 2003 Mar;185(5):1582-9
references.pmid: 12591875
references.citation: J Biol Chem. 1975 Aug 10;250(15):5835-40
references.pmid: 1097444
references.citation: Biochem J. 1990 Oct 1;271(1):139-45
references.pmid: 2121129
references.citation: Methods Enzymol. 2009;459:395-433
references.pmid: 19362649