issue contents
September 2017 issue
![Highlighted illustration](/d/issues/2017/09/00/graphics/coverill.gif)
Cover illustration: Structure of the Pfp1 protease from the hyperthermophilic archaeon Thermococcus thioreducens (Larson & McPherson, p. 749).
research papers
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Updated guidelines are presented for publishing biomolecular small-angle scattering (SAS) experiments so that readers can independently assess the quality of the data and models presented. The focus is on solution scattering experiments with either X-rays (SAXS) or neutrons (SANS), where the primary goal is the generation and testing of three-dimensional models, particularly in the context of integrative/hybrid structural modelling.
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AUSPEX is a new software tool for the statistical analysis of single-crystal X-ray diffraction data. It can be used to identify problems in the data resulting from the experiment itself, image processing, data scaling or conversion.
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Protein structure determination by electron diffraction using a single three-dimensional nanocrystal
A single three-dimensional protein nanocrystal was used for structure determination by electron diffraction. Data were acquired using the rotation method with a Timepix hybrid pixel detector for low-dose data acquisition.
The structure of the Pfp1 intracellular protease from T. thioreducens was solved in two crystal forms: one showing it to be a hexamer and the other a dodecamer. The subunits are disulfide-linked in pairs and the very closely juxtaposed catalytic triads are formed across an interface with amino acids contributed by two separate subunits.
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In order to improve the efficiency of protein crystallization, an alternative approach using the mutation of surface residues was devised based on the results of a statistical analysis of the crystal-packing propensity of amino acids. A systematic crystallization experiment validated the results of the statistical analysis.
High-resolution structures of the Zika virus strain MR766 methyltransferase and helicase proteins are reported.
A pentad mutation of GAPR-1 causes structural changes and shifts the GAPR-1 monomer–dimer equilibrium towards dimerization, which together may prevent its binding to Beclin 1.
PDB reference: pentad mutant of GAPR-1, 5vhg