Cryo-EM at ACA 2022

The 2022 meeting of the American Crystallographic Association in Portland was an inspiring event, addressing a range of both conventional and emerging themes in structural biology. The increasing emphasis at the conference on methods outside the conventional envelope of crystallography, especially cryo-electron microscopy, is discussed.

Towards a new level of qu­antitative treatment of 3D electron diffraction data – in-pattern optical distortions

Electron diffraction patterns unavoidably contain in-plane distortions introduced by electromagnetic lens systems. Geometric correction of different distortion types allows the accuracy of lattice parameter determination to be improved in 3D electron diffraction data.

Making ripples in the comparison of calculated and experimental maps for real-space refinement and assessment by analytic modelling of local resolution

Commentary is given on a paper [Urzhumtsev & Lunin (2022). IUCrJ, 9, 728–734] proposing a new method for the analytic modelling of inhomogeneous resolution in electrostatic potential volumes and electron density maps for improved real-space refinement.

Comparative structural analyses of the NHL domains from the human E3 ligase TRIM–NHL family

Family-wide structural analyses of human TRIM NHL domains reveal evolutionary divergence of their β-propeller architecture that might be essential for recruiting diverse interacting partners and for the roles of NHL domains as E3 ligases.

Analytic modeling of inhomogeneous-resolution maps in cryo-electron microscopy and crystallography

A decomposition of 3D oscillating functions results in analytic expressions for atomic model density maps distorted by inhomogeneous resolution and atomic positional disorder. Such decomposition extends the possibilities of real-space refinement of atomic models.

Accurate lattice parameters from 3D electron diffraction data. I. Optical distortions

Refinement of optical distortions in 3D electron diffraction data allows the determination of accurate lattice parameters and improves intensity integration.

Slow protein dynamics probed by time-resolved oscillation crystallography at room temperature

The use of room-temperature crystallography to probe protein dynamics on the second-to-minute timescale is demonstrated by monitoring the release of a photoequilibrium induced in crystals of a LOV domain. The slow protein dynamics components include the relaxation of a photoadduct and a crystalline phase transition. The result of the latter is the formation of a non-crystallographic dimer in which the C-termini of the two monomers reorder in distinct conformations on different timescales.

Multi-crystal native-SAD phasing at 5 keV with a helium environment

Low-energy native-SAD phasing using a helium path could be used more routinely for solving challenging membrane protein structures.

Rapid and efficient room-temperature serial synchrotron crystallography using the CFEL TapeDrive

Using the CFEL TapeDrive, minimization of sample consumption and data collection times needed for serial synchrotron crystallography (SSX) were achieved and the first room-temperature structures of two enzymes are described as well as an assessment of the benefit of SSX for a radiation-sensitive protein.