Post-translational modification in the archaea: Structural characterization of multi-enzyme complex lipoylation

Mareike G. Posner, Abhishek Upadhyay, Susan J. Crennell, Andrew J.A. Watson, Steve Dorus, Michael J. Danson, Stefan Bagby

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Lipoylation, the covalent attachment of lipoic acid to 2- oxoacid dehydrogenase multi-enzyme complexes, is essential for metabolism in aerobic bacteria and eukarya. In Escherichia coli, lipoylation is catalysed by LplA (lipoate protein ligase) or by LipA (lipoic acid synthetase) and LipB [lipoyl(octanoyl) transferase] combined. Whereas bacterial and eukaryotic LplAs comprise a single two-domain protein, archaeal LplA function typically involves two proteins, LplA-N and LplA-C. In the thermophilic archaeon Thermoplasma acidophilum, LplA-N and LplA-C are encoded by overlapping genes in inverted orientation (lpla-c is upstream of lpla-n). The T. acidophilum LplA-N structure is known, but the LplA-C structure is unknown and LplA-C's role in lipoylation is unclear. In the present study, we have determined the structures of the substrate-free LplA-N-LplA-C complex and E2lipD (dihydrolipoyl acyltransferase lipoyl domain) that is lipoylated by LplA-N-LplA-C, and carried out biochemical analyses of this archaeal lipoylation system. Our data reveal the following: (i) LplA-C is disordered but folds upon association with LplA-N; (ii) LplA-C induces a conformational change in LplA-N involving substantial shortening of a loop that could repress catalytic activity of isolated LplA-N; (iii) the adenylate-binding region of LplA-N-LplA-C includes two helices rather than the purely loop structure of varying order observed in other LplA structures; (iv) LplAN-LplA-C and E2lipD do not interact in the absence of substrate; (v) LplA-N-LplA-C undergoes a conformational change (the details of which are currently undetermined) during lipoylation; and (vi) LplA-N-LplA-C can utilize octanoic acid aswell as lipoic acid as substrate. The elucidated functional inter-dependence of LplA-N and LplA-C is consistent with their evolutionary coretention in archaeal genomes.

Original languageEnglish (US)
Pages (from-to)415-425
Number of pages11
JournalBiochemical Journal
Issue number2
StatePublished - Jan 15 2013


  • Binding-induced folding
  • Lipoate protein ligase
  • Lipoyl domain
  • NMR spectroscopy
  • Protein-protein interaction
  • X-ray crystallography

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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