Abstract
Helicobacter pylori ( H. pylori ) is a gram-negative microaerophilic bacterium that is associated with peptic ulcers, gastric cancer and chronic gastritis. Inorganic pyrophosphatase [E.C.3.6.1.1.] (PPase) is an essential enzyme for energy metabolism in all cells. It catalyzes the hydrolysis of PPi that is synthesized during polymer synthesis and then hydrolyzed to Pi, thus providing a thermodynamic pull favoring polymer synthesis. PPases are strongly dependent on divalent cations. The crystal structure of recombinant PPase from H. pylori (strain: 26695) was reported here. PPase from H. pylori is cytoplasmic and belongs to family I. The molecular weight of H. pylori PPase monomer is about 20 kD. H. pylori PPase is recognized as a hexamer in solution according to the results of ultracentrifugation and gel filtration. The hexameric oligomerization was also seen in the structure. Crystal structures of PPase and PPi-PPase complex were solved here using molecular replacement. The overall PPase structure is composed of two extended α-helices and eight β-strands. Meanwhile, the comparison between H. pylori PPase and E. coli PPase was also described here.