Helicobacter pylori HopQ outer membrane protein attenuates bacterial adherence to gastric epithelial cells

Helicobacter pylori genomes contain about 30 hop genes that encode outer membrane proteins. Helicobacter pylori hopQ alleles exhibit a high level of genetic diversity, and two families of hopQ alleles have been described. Type I hopQ alleles are found more commonly in cag-positive H. pylori strains from patients with peptic ulcer disease than in cag-negative strains from patients without ulcer disease. In this study, we mutated hopQ in four H. pylori strains that each contained a type I hopQ allele, and then analyzed interactions of the wild-type and hopQ mutant strains with AGS cells. In comparison with the wild-type strains, two of the hopQ mutant strains exhibited increased adherence to AGS cells and two hopQ mutants did not exhibit any detectable differences in adherence. Higher levels of tyrosine-phosphorylated CagA were detected when AGS cells were cocultured with a hyperadherent hopQ mutant strain than when cocultured with the corresponding wild-type strain. These data indicate that in some strains of H. pylori, the HopQ protein can attenuate bacterial adherence to gastric epithelial cells.