The leucyl aminopeptidase from Helicobacter pylori is an allosteric enzyme

Abstract

This study describes the cloning, genetic analysis and biochemical characterization of a leucyl aminopeptidase (LAP) from Helicobacter pylori. A gene encoding LAP was cloned from H. pylori and the expressed 55 kDa protein displayed homology to aminopeptidases from Gram-negative bacteria, plants and mammals. This LAP demonstrated amidolytic activity against L-leucine-p-nitroanilide. Optimal activity was observed at pH 8.0 and 45 degrees C, with V(max) of 232 mumol min(-1) (mg protein)(-1) and S(0.5) of 0.65 mM. The data suggest that LAP could be allosteric (n(H)=2.27), with regulatory homohexamers, and its activity was inhibited by ion chelators and enhanced by divalent manganese, cobalt and nickel cations. Bestatin inhibited both LAP activity (IC(50)=49.9 nM) and H. pylori growth in vitro. The results point to the potential use of LAP as a drug target to develop novel anti-H. pylori agents.