Predicting X-ray diffuse scattering from translation-libration-screw structural ensembles
Protein flexibility is essential for enzymatic turnover, signalling regulation and protein-protein interactions. The motions enabling these functions vary in length from a few angstroms to many nanometres and include transitions between side-chain rotamers, loop openings and closings, and rigid-body subunit rotations. Multiple crystal structures are routinely compared to identify these motions and to derive hypotheses about the role of correlated motions in executing protein function. However, if only a single crystal form is available, evidence of concerted motion must be extracted from the spread in the electron density. Diffuse X-ray scattering can help by reporting on correlated atomic displacements. Although recent technological advances are increasing the potential to accurately measure diffuse scattering, computational modelling and validation tools are still needed to quantify the agreement between experimental data and different parameterizations of crystalline disorder. A new tool, phenix.diffuse, addresses this need by calculating diffuse scattering from Protein Data Bank (PDB)-formatted structural...