Identification of the Helicobacter pylori anti-sigma28 factor

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• Flagellar motility is crucial for Helicobacter pylori colonization of the gastric mucosa.
• Gene expression for flagellar components FlaA and FlaB is regulated by sigma28 and sigma54 RNA polymerase factors.
• Previous studies lacked identification of sigma28-specific effectors or anti-sigma28 factors (FlgM) in H. pylori.

Purpose of the Study:

• To investigate the sigma28-dependent regulation of flagellar gene expression in H. pylori.
• To identify and characterize potential regulators of the sigma28 transcription factor.
• To elucidate the role of HP1122 in flagellar synthesis and assembly.

Main Methods:

• Genomic data analysis and two-hybrid screening to identify protein interactions.
• Characterization of the HP1122-sigma28 interaction domain.
• Confirmation of HP1122 function in H. pylori using RNA dot-blot hybridization and electron microscopy.

Main Results:

• HP1122 was identified as a protein interacting with the sigma28 factor, specifically inhibiting its association with RNA polymerase.
• HP1122 functions as an anti-sigma28 factor, regulating flaA transcription.
• Deletion of HP1122 increased flaA transcription, while its overproduction led to truncated flagella, confirming its role in flagellar assembly.

Conclusions:

• HP1122 is identified as the functional anti-sigma28 factor (FlgM) in H. pylori, a critical regulator of flagellar assembly.
• This finding provides insight into the checkpoint mechanisms controlling flagellar synthesis in H. pylori.
• Homologs of HP1122 were identified in other bacterial species, suggesting a conserved regulatory mechanism.