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Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility
Published on: March 11, 2022
Multiple peptidoglycan modification networks modulate Helicobacter pylori's cell shape, motility, and colonization
Laura K Sycuro1, Timna J Wyckoff, Jacob Biboy
1Molecular and Cellular Biology Graduate Program, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.
Plos Pathogens
|March 30, 2012
Summary
The helical shape of Helicobacter pylori enhances stomach colonization by improving mucus penetration, not just swimming speed in viscous environments. This shape is crucial for pathogen survival and virulence in the gastric system.
Area of Science:
- Microbiology
- Cell Biology
- Biophysics
Background:
- The helical cell shape of Helicobacter pylori is hypothesized to enhance virulence via increased swimming velocity in viscous conditions.
- However, mutants lacking helical twist exhibit normal velocity in viscous solutions, leaving their impaired stomach colonization unexplained.
Purpose of the Study:
- To investigate the molecular mechanisms underlying Helicobacter pylori's helical shape and its contribution to virulence.
- To identify novel factors involved in peptidoglycan modification and cell shape determination.
Main Methods:
- Characterization of novel rod-shaped mutants (csd4, csd5) using morphological and biochemical analyses.
- Investigated the role of peptidoglycan (PG) modification, specifically Csd4's tripeptide cleavage and Csd1's crosslinking relaxation, in generating helical shape.
- Assessed motility in various media (viscous solutions, gel-like media) and stomach colonization efficiency of different mutants.
Main Results:
- Identified Csd4 (DL-carboxypeptidase) and Csd5 (scaffolding protein) as key players in generating helical shape through independent PG modification networks.
- csd4 mutants showed reduced stomach colonization but no change in cytokine induction, despite increased Nod1-agonist tripeptides.
- Motility deficits were observed in gel-like media, correlating with shape alterations, but not in simple viscous solutions.
Conclusions:
- Helical cell shape in H. pylori is essential for efficient penetration of the viscoelastic gastric mucus barrier, conferring a significant fitness advantage.
- The study elucidates the independent roles of Csd4 and Csd1 in shaping the bacterial cell envelope, contributing to virulence through enhanced motility in specific environments.
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