title: Assembly of the covalent linkage between lipoic acid and its cognate enzymes.
abstract: Lipoic acid is synthesized from octanoic acid by insertion of sulfur atoms at carbons 6 and 8 and is covalently attached to a pyruvate dehydrogenase (PDH) subunit. We show that sulfur atoms can be inserted into octanoyl moieties attached to a PDH subunit or a derived domain. Escherichia coli lipB mutants grew well when supplemented with octanoate in place of lipoate. Octanoate growth required both lipoate protein ligase (LplA) and LipA, the sulfur insertion protein, suggesting that LplA attached octanoate to the dehydrogenase and LipA then converted the octanoate to lipoate. This pathway was tested by labeling a PDH domain with deuterated octanoate in an E. coli strain devoid of LipA activity. The labeled octanoyl domain was converted to lipoylated domain upon restoration of LipA. Moreover, octanoyl domain and octanoyl-PDH were substrates for sulfur insertion in vitro.
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: J Richard
authors.initials: JR
authors.lastname: Miller
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Jiang
authors.forename: Michael A
authors.initials: MA
authors.lastname: Marletta
authors.forename: John E
authors.initials: JE
authors.lastname: Cronan
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D002210:Caprylates / Q000378:metabolism / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008025:Ligases; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000737:chemistry* / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism; D008063:Thioctic Acid / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002210:Caprylates; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D021122:Protein Subunits; C490345:lplA protein, E coli; C089935:lplA protein, bacteria; D013455:Sulfur; D008063:Thioctic Acid; D030481:Pyruvate Dehydrogenase (Lipoamide); D000217:Acyltransferases; C421483:LipB protein, E coli; D008025:Ligases; C031492:octanoic acid