title: Evidence for two protein-lipoylation activities in Escherichia coli.
abstract: The lipoate acyltransferase subunits of the 2-oxo acid dehydrogenase complexes are post-translationally modified with one or more covalently-bound lipoyl cofactors. Two distinct lipoate-protein ligase activities, LPL-A and LPL-B, have been detected in E. coli by their ability to modify purified lipoyl apo-domains of the bacterial pyruvate dehydrogenase complex. Both enzymes require ATP and Mg2+, use L-lipoate, 8-methyllipoate, lipoyl adenylate and octanoyl adenylate as substrates, and both activate lipoyl-deficient pyruvate dehydrogenase complexes. In contrast, only LPL-B uses D-lipoate and octanoate and there are differences in the metal-ion and phosphate requirements. It is suggested that LPL-B may be responsible for the octanoylation of lipoyl domains observed previously under lipoate-deficient conditions.
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
authors.forename: D E
authors.initials: DE
authors.lastname: Brookfield
authors.forename: J
authors.initials: J
authors.lastname: Green
authors.forename: S T
authors.initials: ST
authors.lastname: Ali
authors.forename: R S
authors.initials: RS
authors.lastname: Machado
authors.forename: J R
authors.initials: JR
authors.lastname: Guest
mesh_terms: D002846:Chromatography, Affinity; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D046911:Macromolecular Substances; D010453:Peptide Synthases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D013379:Substrate Specificity; D008063:Thioctic Acid / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D011768:Pyruvate Dehydrogenase Complex; D008063:Thioctic Acid; D010453:Peptide Synthases; C072322:lipoate-protein ligase