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

Abstract

The use of heavy water (D(2)O) 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 D(2)O in additive screening for the production of reproducible diffraction-quality crystals for the Salmonella enteritidis fimbriae 14 (SEF14) putative tip adhesin, SefD.

Crystal structure and analysis of HdaB: The enteroaggregative Escherichia coli AAF/IV pilus tip protein

“…As anticipated, tertiary structure comparisons using the Dali server identified the EAEC AAF/I and AAF/II tip subunits AggB and AafB as having significant structural homology (RMSD 1.2 Å and 1.4 Å, respectively) with HdaB‐dsA (Table ). In addition, other minor pilin tip members of the Afa/Dr superfamily were also highlighted: the diffusely adherent E. coli (DEAE) AfaD/DraD protein (RMSD 1.8 Å) and the Salmonella enteritidis fimbriae 14 (SEF14) SefD protein (RMSD 1.9 Å) (Table ). The secondary structure elements of these proteins superpose with little deviation; however, variations are localized to regions within the L1, L2 and L3 loops of all four structures [Fig.…”

D2O as an Imperfect Replacement for H2O: Problem or Opportunity for Protein Research?

“… 33 The increased rigidity which Cioni et al have observed for different proteins (see Table 2 ) also supports the idea that protein–solvent interactions are altered in D 2 O: 31 using luminescence methods it was found for 5 proteins out of the 7 analyzed that D 2 O increases protein rigidity, with a protein-dependent rigidity enhancement. In this respect it is interesting to note that some proteins crystallize more efficiently in D 2 O than in H 2 O, 46 a phenomenon that in the case of ref ( 46 ) was even accompanied by a difference in crystal symmetry and structure (whereas in general protein crystal structures seem to be independent of whether H 2 O or D 2 O is used 47 − 49 ). The D 2 O-induced damping of conformational fluctuations can be attributed to stronger solvent–solvent interactions, 31 which reduce protein hydration and promote intramolecular interactions (as was observed in ref ( 32 )).…”