The editors discuss the submission of structural biology data.

A 3D cellular imaging platform developed at beamline B24 at Diamond Light Source has been used to identify cellular features such as filamentous actin in mammalian cells. This approach enabled virtual same-sample imaging of structures captured on separate microscopes through rigid transformation of 3D data in silico, bypassing the need for additional sample processing and ensuring artefact-free data correlation.

A standalone system, called PDB-Dev, has been developed for archiving integrative structures and making them publicly available. The paper describes the data standards, the software tools and the various components of the PDB-Dev data-collection, processing and archiving infrastructure.

Ten goals for the future development of macromolecular refinement programs are described.

MctA is an Mg²⁺-complexed citrate-binding protein from a Gram-negative bacterium that belongs to the ABC transporter superfamily. Comparison of the crystal structures of wild-type and mutant MctA proteins suggest a gating mechanism of substrate entry following an `asymmetric domain movement' mechanism of substrate binding.

Legionella pneumophila protein effector LegA15/AnkD contains an ankyrin-repeat domain, a cysteine protease-like domain with His268–Asn290–Cys361 putative catalytic triad, and a helix-bundle domain. LegA15/AnkD shows structural similarity to another effector, LegA3/AnkH, but they localize to different cellular compartment within the host.

The CIDE domain was initially identified in apoptotic nucleases and now forms a highly conserved family with diverse functions ranging from cell death to lipid metabolism. Based on structural determination of the DREP3 domain, it is suggested that the head-to-tail helical filament structure might be a unified mechanism of CIDE-domain assembly and represents a critical higher-order scaffolding structure that is important for the function of CIDE-domain-containing proteins in DNA fragmentation and lipid-droplet fusion.

Extensive biochemical assays revealed that a putative peptidase S9Cfn from Fusobacterium nucleatum is a carboxypeptidase rather than an aminopeptidase as previously noted. Combined with the 2.6 Å tetramer structure of S9Cfn, key residues for substrate binding and catalysis, as well as the underlying mechanism of the catalytic cycle was revealed for S9C peptidase family.

The X-ray structure of BbgIII, a multidomain β-galactosidase from B. bifidum, determined using an intact protein corresponding to a gene construct of eight domains is reported.

A study of in vitro refolding and isotope effects on protein structure, activity and stability shows that different folding dynamics can lead to important changes in protein properties.

A machine-learning model was used to predict the performance of four crystallographic model-building pipelines (ARP/wARP, Buccaneer, Phenix AutoBuild and SHELXE) and their combinations.

The new CAB automatic model-building program is described and compared with other automated model-building techniques.

The crystal structure of the A. muciniphila arylsulfatase AmAS is reported and some structural regularity of substrate binding and specificity was noted. Insights into the catalytic mechanism of mucin-desulfating sulfatases in A. muciniphila are also provided based on this regularity.