CHARACTERIZATION OF AN ACIDIC-PH-INDUCIBLE STRESS PROTEIN (HSP70), A PUTATIVE SULFATIDE BINDING ADHESIN, FROM HELICOBACTER-PYLORI

The in vitro glycolipid binding specificity of the gastric pathogen He licobacter pylori is altered to include sulfated glycolipids (sulfatid es) following brief exposure of the organism to acid pH typical of the stomach. This change is prevented by anti-hsp70 antibodies, suggestin g that hsp70 may be a stress-induced surface adhesin, mediating sulfat ide recognition. To facilitate investigation of the role of hsp70 in a ttachment, we have cloned and sequenced the H. pylori hsp70 gene (dnaK ). The hsp70 gene was identified by probing a cosmid DNA library made from H. pylori 439 with a PCR amplicon generated with oligonucleotides synthesized to highly conserved regions of dnaK. The 1.9-kb H. pylori hsp70 gene encodes a product of 616 amino acids. Primer extension ana lysis revealed a single transcription start site, while Northern blot analysis established that hsp70 was preferentially induced by low pH r ather than by heat shack. The ability of H. pylori to alter its glycol ipid binding specificity following exposure to low pH by upregulating hsp70 and by expressing hsp70 on the bacterial surface may provide a s urvival advantage during periods of high acid stress.