Cryo-EM structures of apo-APC/C and APC/C complexes provide insights into APC/C regulation.

APC/C is a multi-subunit complex that functions as a master regulator of cell division. It controls progression through the cell cycle by timely marking mitotic cyclins and other cell cycle regulatory proteins for degradation. The APC/C itself is regulated by the sequential action of its coactivator subunits CDC20 and CDH1, post-translational modifications, and its inhibitory binding partners EMI1 and the mitotic checkpoint complex.

Crystal structure of a bacterial photoactivated adenylate cyclase determined by serial femtosecond and serial synchrotron crystallography.

OaPAC is a recently discovered blue-light-using flavin adenosine dinucleotide (BLUF) photoactivated adenylate cyclase from the cyanobacterium Oscillatoria acuminata that uses adenosine triphosphate and translates the light signal into the production of cyclic adenosine monophosphate. Here, we report crystal structures of the enzyme in the absence of its natural substrate determined from room-temperature serial crystallography data collected at both an X-ray free-electron laser and a synchrotron, and we compare these structures with cryo-macromolecular crystallography structures obtained at a synchrotron by us and others. These results reveal slight differences in the structure of the enzyme due to data collection at different temperatures and X-ray sources.

Doses for X-ray and electron diffraction: New features in RADDOSE-3D including intensity decay models.

New features in the dose estimation program RADDOSE-3D are summarised. They include the facility to enter a diffraction intensity decay model which modifies the "Diffraction Weighted Dose" output from a "Fluence Weighted Dose" to a "Diffraction-Decay Weighted Dose", a description of RADDOSE-ED for use in electron diffraction experiments, where dose is historically quoted in electrons/Å rather than in gray (Gy), and finally the development of a RADDOSE-3D GUI, enabling easy access to all the options available in the program.

Identifying and avoiding radiation damage in macromolecular crystallography.

Radiation damage remains one of the major impediments to accurate structure solution in macromolecular crystallography. The artefacts of radiation damage can manifest as structural changes that result in incorrect biological interpretations being drawn from a model, they can reduce the resolution to which data can be collected and they can even prevent structure solution entirely. In this article, we discuss how to identify and mitigate against the effects of radiation damage at each stage in the macromolecular crystal structure-solution pipeline.

Welcoming five new Co-editors.

Five new Co-editors are appointed to the Editorial Board of Acta Cryst. D - Structural Biology.

Radiation damage to biological macromolecules∗.

In this review, we describe recent research developments into radiation damage effects in macromolecular X-ray crystallography observed at synchrotrons and X-ray free electron lasers. Radiation damage in small molecule X-ray crystallography, small angle X-ray scattering experiments, microelectron diffraction, and single particle cryo-electron microscopy is briefly covered.

Raimond B. G. Ravelli (25 March 1968-30 June 2023).

Raimond B. G. Ravelli is remembered.

AlphaFold and the future of structural biology.

This editorial acknowledges the transformative impact of new machine-learning methods, such as the use of AlphaFold, but also makes the case for the continuing need for experimental structural biology.

AlphaFold and the future of structural biology.

This editorial acknowledges the transformative impact of new machine-learning methods, such as the use of AlphaFold, but also makes the case for the continuing need for experimental structural biology.

AlphaFold and the future of structural biology.

This editorial acknowledges the transformative impact of new machine-learning methods, such as the use of AlphaFold, but also makes the case for the continuing need for experimental structural biology.

The CCP4 suite: integrative software for macromolecular crystallography.

The Collaborative Computational Project No. 4 (CCP4) is a UK-led international collective with a mission to develop, test, distribute and promote software for macromolecular crystallography. The CCP4 suite is a multiplatform collection of programs brought together by familiar execution routines, a set of common libraries and graphical interfaces.

Variability in X-ray induced effects in [Rh(COD)Cl] with changing experimental parameters.

X-ray characterisation methods have undoubtedly enabled cutting-edge advances in all aspects of materials research. Despite the enormous breadth of information that can be extracted from these techniques, the challenge of radiation-induced sample change and damage remains prevalent. This is largely due to the emergence of modern, high-intensity X-ray source technologies and the growing potential to carry out more complex, longer duration or studies.

Quantifying and comparing radiation damage in the Protein Data Bank.

Radiation damage remains one of the major bottlenecks to accurate structure solution in protein crystallography. It can induce structural and chemical changes in protein crystals, and is hence an important consideration when assessing the quality and biological veracity of crystal structures in repositories like the Protein Data Bank (PDB). However, detection of radiation damage artefacts has traditionally proved very challenging.

Resolving the subtle details of human DNA alkyltransferase lesion search and repair mechanism by single-molecule studies.

SignificanceWe directly visualize DNA translocation and lesion recognition by the O-alkylguanine DNA alkyltransferase (AGT). Our data show bidirectional movement of AGT monomers and clusters on undamaged DNA that depended on Zn occupancy of AGT. A role of cooperative AGT clusters in enhancing lesion search efficiencies by AGT has previously been proposed.

Heterotypic interactions drive antibody synergy against a malaria vaccine candidate.

Understanding mechanisms of antibody synergy is important for vaccine design and antibody cocktail development. Examples of synergy between antibodies are well-documented, but the mechanisms underlying these relationships often remain poorly understood. The leading blood-stage malaria vaccine candidate, CyRPA, is essential for invasion of Plasmodium falciparum into human erythrocytes.

Submission of structural biology data for review purposes.

The editors discuss the submission of structural biology data.

Submission of structural biology data for review purposes.

The editors discuss the submission of structural biology data.

Submission of structural biology data for review purposes.

The editors discuss the submission of structural biology data.

Radiation damage to biological samples: still a pertinent issue.

An understanding of radiation damage effects suffered by biological samples during structural analysis using both X-rays and electrons is pivotal to obtain reliable molecular models of imaged molecules. This special issue on radiation damage contains six papers reporting analyses of damage from a range of biophysical imaging techniques. For X-ray diffraction, an in-depth study of multi-crystal small-wedge data collection single-wavelength anomalous dispersion phasing protocols is presented, concluding that an absorbed dose of 5 MGy per crystal was optimal to allow reliable phasing.

Zinc determines dynamical properties and aggregation kinetics of human insulin.

Protein aggregation is a widespread process leading to deleterious consequences in the organism, with amyloid aggregates being important not only in biology but also for drug design and biomaterial production. Insulin is a protein largely used in diabetes treatment, and its amyloid aggregation is at the basis of the so-called insulin-derived amyloidosis. Here, we uncover the major role of zinc in both insulin dynamics and aggregation kinetics at low pH, in which the formation of different amyloid superstructures (fibrils and spherulites) can be thermally induced.

Doses for experiments with microbeams and microcrystals: Monte Carlo simulations in RADDOSE-3D.

Increasingly, microbeams and microcrystals are being used for macromolecular crystallography (MX) experiments at synchrotrons. However, radiation damage remains a major concern since it is a fundamental limiting factor affecting the success of macromolecular structure determination. The rate of radiation damage at cryotemperatures is known to be proportional to the absorbed dose, so to optimize experimental outcomes, accurate dose calculations are required which take into account the physics of the interactions of the crystal constituents.