How best to use photons

Different modes of data collection are explored, and the effect of flux and multiplicity on the resulting quality of the data set is discussed. Advice is offered on how to collect data in the absence of prior knowledge of the sample.

Making routine native SAD a reality: lessons from beamline X06DA at the Swiss Light Source

A broadly applicable, simple and fast data-collection strategy for native SAD is described, which has become the primary choice for experimental phasing among users of the macromolecular crystallography beamline X06DA (PXIII) at the Swiss Light Source. Its usage over the last four years is reviewed.

Solution structures of long-acting insulin analogues and their complexes with albumin

Solution structures of complexes between human serum albumin and the two lipidated insulin analogues detemir and degludec are presented and models for the equilibria are suggested.

The atypical thiol–di­sulfide exchange protein α-DsbA2 from Wolbachia pipientis is a homotrimeric di­sulfide isomerase

The disulfide isomerase α-DsbA2 from Wolbachia pipientisis is unexpectedly homotrimeric and lacks the `shape-shifting' conformational flexibility that defines another trimeric disulfide isomerase, ScsC from Proteus mirabilis.

Engineered variants provide new insight into the structural properties important for activity of the highly dynamic, trimeric protein di­sulfide isomerase ScsC from Proteus mirabilis

The structure and function of a bacterial trimeric protein disulfide isomerase was investigated by characterising two variants in which key structural regions were deleted. In one case the effect on structure and function was predictable, while in the other we found unintended consequences for both structure and function.

Crystal structures of pyrrolidone-carboxylate peptidase I from Deinococcus radiodurans reveal the mechanism of L-pyroglutamate recognition

The crystal structure of pyroglutamate (pG) bound PCP I enzyme reveals the mechanism of its pG specificity. The residues of a conserved active-site loop interact with pG via phenylalanine stacking interactions and hydrogen bonds.

In-house high-energy-remote SAD phasing using the magic triangle: how to tackle the P1 low symmetry using multiple orientations of the same crystal of human IBA57 to increase the multiplicity

This article describes the methodological approach used to solve the structure of human IBA57; to our knowledge, this is the only structure present in the Protein Data Bank which has been solved in-house by remote SAD phasing in space group P1 using only one crystal.

X-ray structure of an inactive zymogen clostripain-like protease from Parabacteroides distasonis

Cysteine proteases are among the most prominent hydrolytic enzymes produced by human distal gut commensal bacteria. Here, the first inactive zymogen structure of a clostripain-like C11 protease family member is reported from the bacterium Parabacteroides distasonis.

A 60-heme reductase complex from an anammox bacterium shows an extended electron transfer pathway

The heterododecameric complex of a reducing octaheme cytochrome c with its redox partner shows an extended electron transfer pathway.

Coping with strong translational noncrystallographic symmetry and extreme anisotropy in molecular replacement with Phaser: human Rab27a

The solution of a structure of human Rab27a suffering from severe anisotropy and translational noncrystallographic symmetry was aided by identifying diffraction measurements with low information content.

Thomas A. Steitz (1940–2018)

Nobel Prize winner Tom Steitz is remembered by his former colleague Poul Nissen.