Crystal-packing analysis of translation initiation factor 2 reveals new details of its function

A comparative analysis of the known crystal structures of the archaeal translation initiation factor 2 from Sulfolobus solfataricus and its individual subunits is reported. This work confirms the leading role of switch 1 in the function of the γ subunit of translation initiation factor 2 and reveals some important new details of this process.

The crystal structure of the N-terminal domain of the backbone pilin LrpA reveals a new closure-and-twist motion for assembling dynamic pili in Ligilactobacillus ruminis

Linear and bent conformations of the backbone pilin LrpA from the gut-dwelling Ligilactobacillus ruminis have been determined by X-ray crystallography and SAXS. The hinge region connecting the flexible N-terminal domain to the other two domains lets LrpA be assembled into dynamic pili via a new closure-and-twist motion, enabling these surface structures to reach host receptor sites and withstand shear forces during intestinal colonization.

Validation of electron-microscopy maps using solution small-angle X-ray scattering

A novel validation tool for transmission electron-microscopy maps utilizing independent small-angle X-ray scattering measurements is introduced and implemented. The power of this technique was demonstrated by testing it using simulated data and using it on real experimental data from online repositories.

Towards a dependable data set of structures for L-asparaginase research

The crystallographic structures of asparaginases of class 1 (bacterial-type), class 2 (plant-type) and class 3 (Rhizobium etli-type) in the PDB are reviewed in order to identify and, if possible, correct any modeling errors, with the purpose of creating a reliable data set for further research, including the development of new antileukemic agents.

Deep-learning map segmentation for protein X-ray crystallographic structure determination

Electron-density map segmentation into protein and solvent regions using deep neural networks improves density modification in X-ray structure solution from experimental phases.

Factors affecting macromolecule orientations in thin films formed in cryo-EM

Preferred orientation of macromolecules is one of the major issues that are commonly encountered in obtaining isotropic cryo-EM maps. Here, a comprehensive examination was performed of how macromolecule orientations respond to changes in physical factors, such as freezing temperature, and chemical factors, such as the addition of surfactants, for a standard set of macromolecules, which provides insights into their behaviour on grids and can be utilized to address the preferred orientation problem in a systemic manner for any given macromolecule.

A structural role for tryptophan in proteins, and the ubiquitous Trp C^δ1—H⋯O=C (backbone) hydrogen bond

A set of hydrogen bonds which occur in proteins between the C^δ1—H donor group of the tryptophan indole and main-chain carbonyl O atoms separated by 1–4 peptide units were characterized. These interactions stabilize unique and functionally important structural motifs and noncanonical side-chain conformations of tryptophan.