Helicobacter urease: Niche construction at the single molecule level.

The urease of the human pathogen, Helicobacter pylori, is essential for pathogenesis. The ammonia produced by the enzyme neutralizes stomach acid; thereby modifying its environment. The dodecameric enzyme complex has high affi nity for its substrate, urea. We compared urease sequences and derivative 3D homology model structures from all published Helicobacter genomes and an equal number of genomes belonging to strains of another enteric bacterium, Escherichia coli. We found that the enzyme’s architecture adapts to fi t its niche. This fi nding, coupled to a survey of other physiological features responsible for the bacterium’s acid resistance, suggests how it copes with pH changes caused by disease onset and progression.