Structural and enzymatic characterization of HPO496, a YbgC thioesterase from Helicobacter pylori

YbgC proteins are bacterial acyl-CoA thioesterases associated with the Tol-Pal system. This system is important for cell envelope integrity and is part of the cell division machinery. In E. coli, YbgC associates with the cell membrane and is part of a protein network involved in lipid biogenesis. In the human pathogen Helicobacter pylori, a putative homologue of YbgC, named HP0496, was found to interact with the cytotoxin CagA by two different studies. We have determined its crystal structure and characterized its enzymatic activity. The structure of HP0496 shows that it is a member of the hot-dog family of proteins, with a epsilon gamma tetrameric arrangement. Finally, enzymatic assays performed with the purified protein showed that HP0496 is an acyl-CoA thioesterase that favors long-chain substrates.