Helicobacter pylori: a pathogenic plot twist on the straight rod story
The diversity of shapes that bacteria exhibit has fascinated microbiologists for more than 300 years. Bacteria use their shapes to navigate complex environments to find nutrients, evade host detection, and colonize new areas. Bacteria are incredibly small (200-2000 nanometers) and therefore cannot be easily imaged by standard microscopy techniques. I have developed advanced fluorescence microscopy technologies and computational imaging software to reconstruct the 3D shape of individual bacterial cells. In particular, I’ve been studying the shape of the human stomach pathogen Helicobacter pylori, which causes ulcers and gastric cancer. We now have a handful of proteins which act to build the rigid cell wall, the shape-defining component of the cell. Mutants which lack these proteins no longer form the stereotypical helical-rod morphology and show a defect in colonizing hosts. Using my technology, we are now able to see where the cell positions these proteins and where the it builds new wall. As it turns out, H. pylori uses a combination of a widely conserved rod-defining system and an additional protein along the longer, major-helical axis. In contrast, another curved human pathogen, Vibrio cholerae, positions its curvature defining proteins on the shorter, minor helical axis. As we continue to probe additional bacterial species, one thing is clear: getting into shape is important for bacterial cells but there are multiple ways for cells to work this out.