Promoting crystallisation of the Salmonella enteritidis fimbriae 14 pilin SefD using deuterium oxide

Highlights: ► The benefits of D2O in screening for crystallisation was explored. ► The crystal structures of the SefD pilin in both H2O and D2O reveal differences. ► Crystallisation improvements are explained by altered interactions in D2O crystals. ► D2O is useful additive in sparse-matrix screening for crystallisation. -- Abstract: The use of heavy water (D2O) as a solvent is commonplace in many spectroscopic techniques for the study of biological macromolecules. A significant deuterium isotope effect exists where hydrogen-bonding is important, such as in protein stability, dynamics and assembly. Here we illustrate the use of D2O in additive screening for the production of reproducible diffraction-quality crystals for the Salmonella enteritidis fimbriae 14 (SEF14) putative tip adhesin, SefD.