The gastric pathogen helicobacter pylori is one of a number of bacteria which bind specifically to
gangliotetraosylceramide, gangliotriaosylceramide, and
phosphatidylethanolamine in vitro at neutral pH. Since this organism encounters an
acid pH during initial
infection of the stomach, we have monitored the effect of pH on receptor binding specificity and found induction of specific binding to
sulfoglycolipids (
sulfatide) following brief treatment at low pH. We have previously shown that
heat shock proteins (hsps) bind to
sulfatide, and the suspicion that this was a stress-induced response is supported by the fact that a similar change in H. pylori binding specificity was observed if the organisms were briefly exposed to heat shock treatment. Following the stress stimulus, the change in
glycolipid binding specificity was prevented by the inclusion of inhibitors of
protein synthesis or by incubation with anti-hsp
antibodies. Expression of hsps in the surface extract and surface reactivity with anti-hsp
antibodies correlated with the change in
glycolipid binding specificity. Despite the presence of high levels of H. pylori cell surface
urease activity which may neutralize the microenvironmental pH, the
acid-induced change in binding specificity was enhanced in the presence of
urea. These studies suggest that cell surface hsps mediate
sulfatide recognition by this organism under stress conditions. A binary receptor model is proposed for gastric colonization by H. pylori.