Protein–protein interaction of HP137 with histidine kinase HP244 does not contribute to flagellar regulation in Helicobacter pylori

Summary Flagellar motility is essential for the ability of Helicobacter pylori to colonize the gastric mucosa. Expression of the flagella is controlled by a complex regulatory cascade involving the two-component system FlgR-HP244, the sigma factors σ 54 and σ 28 and the anti- σ 28 factor FlgM. The protein–protein interaction map of H. pylori , which is based on a high-throughput two-hybrid screen (Rain et al., 2001. Nature 409, 211–215) indicated a protein–protein interaction between the gene product of ORF hp137 and both the histidine kinase HP244 and the flagellar hook protein HP908. We hypothesized that HP137 might be involved in a feedback regulatory mechanism controlling the activity of histidine kinase HP244. Here we demonstrate that HP137 does not participate in the regulation of flagellar gene expression, neither in H. pylori nor in the closely related bacterium Campylobacter jejuni .