Neutron Crystallography Study of Host–Pathogen Recognition Enhanced by Hydrogen/Deuterium Exchange on Carbohydrates

Neutron macromolecular crystallography (NMX) is a unique tool for location of hydrogen atoms. Its application is greatly enhanced by the use of deuterium‐labeled molecules. Human glycans are the targets of virulence factors from pathogens, such as the soluble lectins from the opportunistic bacterium Pseudomonas aeruginosa . Deuterated galactose was obtained by hydrogen isotope exchange and cocrystallized with a fully deuterated bacterial receptor, LecA, a lectin involved in P. aeruginosa tissue adhesion and biofilm formation. The structure of the complex determined using neutron diffraction reveals the positions of all hydrogen atoms, as deuterium, highlighting the important role of a charged histidine in the binding site, the bridging by a buried water molecule and the influence of the coordinating calcium ion on the adjacent hydrogen bonds. LecA is a target for pathoblockers and these structural details can assist in the design of glycomimetics for fighting multidrug resistant infections.