Glutamine-induced production and secretion of Helicobacter pylori gamma-glutamyltranspeptidase at low pH and its putative role in glutathione transport.

Helicobacter pylori increased the gamma-glutamyltranspeptidase (GGT) production under low-pH (maximal at pH 4) and appropriate pCO2 conditions, while the production of GGT mRNA correlated with increased total enzyme activity. At pH 4, the bacterium augmented enzyme production in the presence of glutamine (~10 mM) in the medium, which predominantly occurred after a 6-min time-lag. Monovalent salts such as NaCl or NH4Cl facilitated enzymatic activation in acidic solutions of approximately pH 4.5. In addition, glutathione's gamma-glutamyl moiety cysteinylglycine appeared to be taken up readily by the intact H. pylori, but not by the one pretreated with a potent GGT inhibitor, acivicin, suggesting that the GGT may partake in glutathione uptake by the cell.