Abstract
Helicobacter pylori (H. pylori) is a gram-negative microaerophilic bacterium that causes chronic gastritis and stomach cancer. Coenzyme A (CoA) is an essential cofactor in all living organisms, which participates in numerous metabolic pathways. For this reason, we choose phosphopantetheine adenylytransferase (PPAT) as a target protein in our research, which is the rate-limiting enzyme in CoA biosynthesis. To investigate the PPAT catalytic mechanism, complex structures of H. pylori PPAT with other ligands, including ATP, phosphopantetheine, and CoA have been determined. Structural comparisons between apo-form PPAT and complex form have been performed and identified some critical residues interacting with these ligands. We randomly mutated the residues in the Helicobacter pylori PPAT sequence and described the crystal structure of one of these mutants (I4V/N76Y). Unlike other PPATs, which are homohexamers, I4V/N76Y is a domain-swapped homotetramer. These two structures between wild-type PPAT and I4V/N76Y PPAT have been characterized by circular dichroism, enzyme kinetics, and crystallography approaches. In addition, structure based high-throughput screen has been employed and some compounds have been utilized to examine the potent inhibitor to inhibit H. pylori PPAT activity. This may provide valuable information for drug design to against the H. pylori infection in the future.