Motility is an essential colonization factor for the human gastric pathogen Helicobacter pylori. The H. pylori genome encodes most known flagellar proteins, although a number of key transcription regulators, chaperones, and structural proteins have not yet been identified. Using recently published yeast two-hybrid data we identified HP0958 as a potential motility-associated protein due to its strong interactions with RpoN (sigma(54)) and FliH, a flagellar ATPase regulator. HP0958 exhibits no sequence similarity to any published flagellar genes but contains a carboxy-terminal zinc finger domain that could function in nucleic acid or protein binding. We created a HP0958 mutant by inserting a chloramphenicol resistance marker into the gene using a PCR-based allelic exchange method and the resultant mutant was non-motile as measured by a BacTracker instrument. Electron microscopic analysis revealed that the HP0958 mutant cells were aflagellate and Western blot analysis revealed a dramatic reduction in flagellin and hook protein production. The HP0958 mutant also showed decreased transcription of flgE, flaB and flaA as well as the checkpoint genes flhA and flhF. Expression of flgM was increased relative to the wild-type and both rpoN and fliA (sigma(28)) expression were unchanged. We conclude that HP0958 is essential for normal motility and flagella production, and represents a novel flagellar component in the epsilon proteobacteria.

Helicobacter pylori is a human gastric pathogen which is dependent on motility for infection. The H. pylori genome encodes a near-complete complement of flagellar proteins compared to model enteric bacteria. One of the few flagellar genes not annotated in H. pylori is that encoding FliK, a hook length control protein whose absence leads to a polyhook phenotype in Salmonella enterica. We investigated the role of the H.

Volume 187, no. 16, p. 5742-5750, 2005. Attempts to extend the observation of complementation of a Salmonella fliK mutant by HP0906 to orthologous genes led to the discovery that the apparent restoration of motility by expression of HP0906 in the Salmonella fliK mutant strain SJW108 was actually due to reversion of the fliK mutation. This reversion occurred in the transformant with the pQE60-HP0906 construct. Expression of HP0906 does not complement Salmonella fliK, and the apparent motility in Fig. 7C (labeled SJW108/pQE60-HP0906) is incorrect. The bioinformatic, ultrastructural, motility, and regulatory data identifying HP0906 as fliK are unaffected, and the main conclusion remains unchanged. 6046on May 9, 2018 by guest