Abstact

Lipoic acid is an essential prosthetic group in several metabolic pathways. The biosynthetic pathway of protein lipoylation in Escherichia coli involves gene products of the lip operon. YbeD is a conserved bacterial protein located in the dacA-lipB intergenic region. Here, we report the nuclear magnetic resonance structure of YbeD from E. coli. The structure includes a beta alpha beta beta alpha beta fold with two alpha-helices on one side of a four-strand antiparallel beta-sheet. The beta 2-beta 3 loop shows the highest sequence conservation and is likely functionally important. The beta-sheet surface contains a patch of conserved hydrophobic residues, suggesting a role in protein-protein interactions. YbeD shows striking structural homology to the regulatory domain from d-3-phosphoglycerate dehydrogenase, hinting at a role in the allosteric regulation of lipoic acid biosynthesis or the glycine cleavage system.