Mutants of Escherichia coli K-12 that are resistant to a selenium analog of lipoic acid identify unknown genes in lipoate metabolism.

Reed, Kelynne E.; Morris, Timothy W.; Cronan, John E.

doi:10.1073/pnas.91.9.3720

Cited by 33 publications

(44 citation statements)

References 14 publications

(14 reference statements)

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“…During the characterization of E. coli lplA null mutant strains, compelling evidence was found for a second protein lipoylation pathway that did not require the lplA gene product (44,45,70). When independently derived lplA null mutations were introduced into wild-type strains, the resulting mutant strains had active (therefore, lipoylated) 2-oxoacid dehydrogenases.…”

Section: The Octanoyl-acp:protein N-octanoyltransferases (Lipb and Lipm)mentioning

confidence: 99%

“…Mutants with mutations mapping in lplA were also isolated by a direct selection mechanism, resistance to selenolipoic acid. Selenolipoic acid is a growth-inhibitory lipoate analogue in which the sulfur atoms are replaced with selenium (45). These mutants encoded a ligase of somewhat compromised activity that was able to discriminate against the larger selenium atoms.…”

Section: Attachment Of Lipoic Acidmentioning

confidence: 99%

“…The lplA gene was the first gene encoding a lipoate-protein ligase, and LplA was the first such ligase purified to homogeneity (43,44). Mutants with mutations in lplA were isolated by two different approaches (44,45). In the first approach, an lipA strain was mutagenized by transposon insertion and the mutagenized cells were supplemented with a mixture of succinate and acetate, which bypasses the lipoate requirement.…”

Section: Attachment Of Lipoic Acidmentioning

confidence: 99%

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Assembly of Lipoic Acid on Its Cognate Enzymes: an Extraordinary and Essential Biosynthetic Pathway

Cronan

2016

Microbiol Mol Biol Rev

125

137

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SUMMARYAlthough the structure of lipoic acid and its role in bacterial metabolism were clear over 50 years ago, it is only in the past decade that the pathways of biosynthesis of this universally conserved cofactor have become understood. Unlike most cofactors, lipoic acid must be covalently bound to its cognate enzyme proteins (the 2-oxoacid dehydrogenases and the glycine cleavage system) in order to function in central metabolism. Indeed, the cofactor is assembled on its cognate proteins rather than being assembled and subsequently attached as in the typical pathway, like that of biotin attachment. The first lipoate biosynthetic pathway determined was that ofEscherichia coli, which utilizes two enzymes to form the active lipoylated protein from a fatty acid biosynthetic intermediate. Recently, a more complex pathway requiring four proteins was discovered inBacillus subtilis, which is probably an evolutionary relic. This pathway requires the H protein of the glycine cleavage system of single-carbon metabolism to form active (lipoyl) 2-oxoacid dehydrogenases. The bacterial pathways inform the lipoate pathways of eukaryotic organisms. Plants use theE. colipathway, whereas mammals and fungi probably use theB. subtilispathway. The lipoate metabolism enzymes (except those of sulfur insertion) are members of PFAM family PF03099 (the cofactor transferase family). Although these enzymes share some sequence similarity, they catalyze three markedly distinct enzyme reactions, making the usual assignment of function based on alignments prone to frequent mistaken annotations. This state of affairs has possibly clouded the interpretation of one of the disorders of human lipoate metabolism.

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Section: The Octanoyl-acp:protein N-octanoyltransferases (Lipb and Lipm)mentioning

confidence: 99%

Section: Attachment Of Lipoic Acidmentioning

confidence: 99%

Section: Attachment Of Lipoic Acidmentioning

confidence: 99%

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Assembly of Lipoic Acid on Its Cognate Enzymes: an Extraordinary and Essential Biosynthetic Pathway

Cronan

2016

Microbiol Mol Biol Rev

125

137

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“…2D), was synthesized, and E. coli mutants resistant to the analog were isolated (32). Se-lip has the same carbon backbone as lipoic acid with selenium atoms substituted for the two sulfur atoms ( Fig.…”

mentioning

confidence: 99%

“…2C and D). Se-lip is taken up by wild-type E. coli and used to modify lipoyl domains (32). This aberrant modification of lipoyl domains leads to inactive 2-oxo acid dehydrogenase complexes, since Se-lip cannot be reduced in vivo (32).…”

mentioning

confidence: 99%

Chromosomal Amplification of the Escherichia coli lipB Region Confers High-Level Resistance to Selenolipoic Acid

Jordan¹,

Cronan

2002

J Bacteriol

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One of the mutants (slr7 mutant) of a wild-type Escherichia coli strain resistant to selenolipoic acid reported previously (K. E. Reed, T. W. Morris, and J. E. Cronan, Jr., Proc. Natl. Acad. Sci. USA 91:3720-3724, 1994) unexpectedly grew on minimal medium following transductional introduction of a lipA null mutation. We report that the slr7 strain carries a duplication of the lip chromosomal region that causes the phenotype of the mutant strain

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The fingerprint of antimitochondrial antibodies and the etiology of primary biliary cholangitis

et al. 2017

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The identification of environmental factors that lead to loss of tolerance has been coined the Holy Grail of autoimmunity. Our work has focused on the reactivity of antimitochondrial autoantibodies (AMA) to chemical xenobiotics and has hypothesized that a modified peptide within PDC-E2, the major mitochondrial autoantigen, will have been immunologically recognized at the time of loss of tolerance. Herein we successfully applied intein technology to construct a PDC-E2 protein fragment containing amino acid residues 177–314 of PDC-E2 by joining a recombinant peptide spanning residues 177 to 252 (PDC-228) with a 62 residue synthetic peptide from 253 to 314 (PP), which encompasses PDC-E2 ILD. We named this intein-constructed fragment PPL. Importantly, PPL, as well as lipoic acid conjugated PPL (LA-PPL) and xenobiotic 2-octynoic acid conjugated PPL (2OA-PPL), are recognized by AMA. Of great importance, AMA has specificity for the 2OA modified PDC-E2 ILD peptide backbone distinct from antibodies that react with native lipoylated PDC-E2 peptide. Interestingly, this unique AMA subfraction is of the IgM isotype and more dominant in early stage PBC, suggesting that exposure to 2OA-PPL-like compounds occurs early in the generation of AMA. To understand the structural basis of this differential recognition we analyzed PPL, LA-PPL and 2OA-PPL using electron paramagnetic resonance spectroscopy, with confirmations by ELISA, immunoblotting and affinity antibody analysis. We demonstrate that the conformation of PDC-E2 ILD is altered when conjugated with 2OA, compared to conjugation with lipoic acid. In conclusion a molecular understanding of the conformation of xenobiotic modified PDC-E2 is critical for understanding xenobiotic modification and loss of tolerance in PBC with widespread implications for a role of environmental chemicals in the induction of autoimmunity.

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Mutants of Escherichia coli K-12 that are resistant to a selenium analog of lipoic acid identify unknown genes in lipoate metabolism.

Abstract: Lipoic acid is a disulfide-containing cofactor required for the reactions catalyzed by a-ketoacid dehydroge-

Cited by 33 publications

References 14 publications

Assembly of Lipoic Acid on Its Cognate Enzymes: an Extraordinary and Essential Biosynthetic Pathway

Assembly of Lipoic Acid on Its Cognate Enzymes: an Extraordinary and Essential Biosynthetic Pathway

Chromosomal Amplification of the Escherichia coli lipB Region Confers High-Level Resistance to Selenolipoic Acid

The fingerprint of antimitochondrial antibodies and the etiology of primary biliary cholangitis

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