Molecular Architecture of the 40S⋅eIF1⋅eIF3 Translation Initiation Complex

Eukaryotic translation initiation requires the recruitment of the large, multiprotein eIF3 complex to the 40S ribosomal subunit. Using X-ray structures of all major components of the minimal, six-subunit Saccharomyces cerevisiae eIF3 core, together with cross-linking coupled to mass spectrometry, we were able to use IMP to position and orient all eIF3 components on the 40S•eIF1 complex, revealing an extended, modular arrangement of eIF3 subunits. For more information about how to reproduce this modeling, see https://salilab.org/40S-eIF1-eIF3 or the README file

Direct transfer of electron microscopy samples to wetted carbon and graphene films via a support floatation block

Support films are commonly used during cryo-EM specimen preparation to both immobilise the sample and minimise the exposure of particles at the air-water interface. Here we report preparation protocols for carbon and graphene supported single particle electron microscopy samples using a novel 3D-printed sample transfer block to facilitate the direct, wetted, movement of both carbon and graphene supports from the substrate on which they were generated to small volumes (10 μL) of sample. These approaches are simple and inexpensive to implement, minimise hydrophobic contamination of the support films, and are widely applicable to single particle studies. Our approach also allows the direct exchange of the sample buffer on the support film in cases in which it is unsuitable for vitrification, e.g. for samples from centrifugal density gradients that help to preserve sample integrity. © 2020 The AuthorsISSN:1047-8477ISSN:1095-865

Architecture of the human mTORC2 core complex

ISSN:2050-084