When Helicobacter pylori bacteria take up long-term residence in human stomachs, the persistent infection can cause ulcers and stomach cancer. A team of researchers led by Tina Howard at AstraZeneca and Franco H. Falcone at the University of Nottingham, in England, has now revealed how H. pylori maintains a tenacious hold in the human stomach (Sci. Adv. 2015, DOI: 10.1126/sciadv.1500315). The team obtained the 2-Å X-ray crystal structure of a protein called BabA found in H. pylori’s external membrane. The pathogen uses BabA to bind sugars found on epithelial cells that line the stomach wall. The team solved BabA’s structure in the presence of a six-sugar human bait found in individuals with O-type blood, who are particularly vulnerable to H. pylori infections. The team discovered that BabA, which is primarily an α-helical protein, has a β-strand domain that acts as the pathogen’s “hand.” Amino acids in the β-strand form hydrogen bonds with O-type blood sugars, grabbing onto them. The team hopes to find small molecules that interrupt these hydrogen bonds and consequently block H. pylori infections.