Transcriptional Analysis of Major Heat Shock Genes of

The transcriptional organization and heat inducibility of the major heat shock genes hrcA, dnaK, dnaJ, groEL, and htpG were analyzed on the transcriptional level in Helicobacter pylori strain 69A. The strongly heat-induced dnaK operon was found to be tricistronic, consisting of the genes hrcA, grpE, and dnaK. The dnaJ gene specified one monocistronic mRNA which was also heat inducible. The genes groES and groEL were transcribed as one strongly heat-inducible bicistronic mRNA which exhibited exactly the same induction kinetic as the dnaK operon. Surprisingly, transcription of the monocistronic htpG gene was switched off after heat shock. The data presented are discussed with regard to the different mechanisms regulating expression of heat shock genes in H. pylori Helicobacter pylori is a gram-negative, spiral-shaped patho-genic bacterium that specifically colonizes the gastric epithe-lium of primates and is the causative agent of chronic, active type B gastritis in humans (3). The following genetic determi-nants contribute to the successful colonization of the gastric mucosa: a urease neutralizing the bacterial microenvironment by producing ammonia from the urea present in mucosal sec