Helicobacter pylori's Helical Shape Promotes Gastric Colonization

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New research has determined for the first time that, at least when it comes to Helicobacter pylori's (Figure 1) ability to colonize the stomach, shape matters.

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• Figure 1. 

  Helicobacter pylori

In a study reported in the May 28 issue of Cell, microbiologist Nina Salama, PhD, and colleagues at the Fred Hutchinson Cancer Research Center and the University of Washington in Seattle discovered a family of LytM peptidase homologs—3 peptidases and a scaffolding protein—that collaborate in generating the bacterium's helical shape.

Using a mouse model, the researchers found that laboratory-engineered mutant strains of H pylori that were deficient in these cell wall proteins fail to twist properly and, consequently, are unable to colonize the gastric mucosa.

The study further determined that the helical shape of H pylori requires relaxation of peptidoglycan cross-linking. “The crosslinks preserve the structural integrity of the bacterial wall, but if certain links are cleaved or relaxed by these proteins, it allows the rod shape to twist into a helix,” Salama said.

Other disease-inducing bacteria that harbor these proteins include Vibrio cholera and Campylobacter jejuni. Thus, it seems that unlocking the keys to H pylori's helical structure may lead to better antibiotic drugs for diseases ranging from ulcers and stomach cancer to diarrhea and cholera.

“In this work, we have established H pylori as an excellent model to elucidate molecular determinants of helical cell shape in the Proteobacteria and the selective role of shape during host colonization,” the authors state. “Our discovery of a family of LytM peptidase homologs required for efficient stomach colonization by H pylori suggests new targets for antimicrobial therapy that may have efficacy in other pathogens that utilize these proteins, including Vibrio and Campylobacter species.” See: http://www.cell.com/fulltext/S0092-8674(10)00365-X.