issue contents

Journal logoSTRUCTURAL
ISSN: 2059-7983

November 2020 issue

Highlighted illustration

Cover illustration: Lattice-translocation defects in toad neuraminidase [Li et al. (2020), Acta Cryst. D76, 1057-1064]. Neuraminidase (NA) inhibitors are one of the two major classes of antivirals available for the treatment and prevention of influenza. X-ray crystal structure determination of NA head domains and their complexes with various inhibitors are of importance for the design and optimization of anti-influenza drugs. However, the globular tetrameric properties of NA head domains may produce crystals with pathological imperfections, lattice-translocation defects, making structure determination no longer straightforward. Here a crystal of the NA head domain from the Wuhan Asiatic toad influenza virus provides an example of the identification and solution of this type of crystal pathology.


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A large single crystal of the Y116S variant of transthyretin was grown and neutron diffraction data were collected to 1.9 Å resolution using the IBARAKI biological crystal diffractometer (iBIX) at the Japan Proton Accelerator Research Complex (J-PARC).

research papers

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Crystallization of the tetramer of the head domain of influenza neuraminidase (NA) may result in a specific crystal with space group C2221 and unit-cell parameters a ≃ 120, b ≃ 143, c ≃ 120 Å. The molecular packing of NA tetramers in this crystal intrinsically causes pathological imperfections, lattice-translocation defects, which complicate the structure determination.

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Replacing the filter paper used in conventional cryoEM specimen preparation with a glass-fiber filter allows specimens to be prepared by wicking solution through the grid. A new device that uses this approach was constructed, and can freeze high-quality specimens in tens of milliseconds.

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An investigation of the structural differences between three newly determined cellobiose 2-epimerases (CEs) and other enzymes in the N-acyl-D-glucosamine 2-epimerase superfamily suggested that it was highly possible that His196 in Spirochaeta thermophila CE was involved in catalyzing isomerization. Rearrangement of the flexible loop during catalysis was significantly involved in the bifunction of this CE and the intermolecular interactions inside the flexible loop greatly influenced the reshaping of the loop and the catalytic direction.

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A structure of the Hazara virus ovarian tumour domain protease (OTU) bound to ubiquitin was elucidated to 2.78 Å resolution. Through structure-guided site-directed mutagenesis, OTUs were engineered to shift the OTU substrate preference from ubiquitin to interferon-stimulated gene product 15.

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The structure of a fungal α-L-arabinofuranosidase has been determined using sulfur SAD data collected in vacuo using beamline I23 at Diamond Light Source. Complexes with L-arabinose, an iminosugar and two covalent inhibitors confirm the identity of the catalytic nucleophile and provide a detailed map of enzyme–substrate interactions that are conserved between bacteria and fungi.

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Separating multi-data sets based on Cα differences can help to identify additional hits for drug- and fragment-screening crystallography experiments, expanding the range of crystal systems to which this technique can be applied. This is made available in a graphical user interface.

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The method of quantum refinement has been extended to systems with multiple conformations in the quantum system. It has been used to improve the description of the P-cluster in three different oxidation states in two crystal structures of the enzyme nitrogenase.

book reviews

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