Single-particle cryo-EM at atomic resolution
The three-dimensional positions of atoms in protein molecules define their structure and provide mechanistic insights into the roles they perform in complex biological processes. The more precisely atomic coordinates are determined, the more chemical information can be derived and the more knowledge about protein function may be inferred. With breakthroughs in electron detection and image processing technology, electron cryo- microscopy (cryo-EM) single-particle analysis has yielded protein structures with increasing levels of detail in recent years. However, obtaining cryo-EM reconstructions with sufficient resolution to visualise individual atoms in proteins has thus far been elusive. A. Radu Aricescu & Sjors H.W. Scheres et al. show in the bioRxiv paper that using a new electron source, energy filter and camera, a 1.7 Å resolution cryo-EM reconstruction for a prototypical human membrane protein, the β3 GABAA receptor homo-pentamer, can be obtained. Such maps allow a detailed understanding of small molecule coordination, visualisation of solvent molecules and alternative conformations for multiple amino acids, as well as unambiguous building of ordered acidic side chains and glycans. Applied to mouse apo-ferritin, their strategy led to a 1.2 Å resolution reconstruction that, for the first time, offers a genuine atomic resolution view of a protein molecule using single particle cryo-EM. Moreover, the scattering potential from many hydrogen atoms can be visualised in difference maps, allowing a direct analysis of hydrogen bonding networks. Combination of the technological advances described here with further approaches to accelerate data acquisition and improve sample quality provide a route towards routine application of cryo-EM in high-throughput screening of small molecule modulators and structure-based drug discovery.
Upgrade of the workflow for cryo-electron tomography and microscopy
The CIISB Cryo-electron microscopy core facility at CEITEC Masaryk University is expanding its services in the sample preparation for electron microscopy. The facility has recently acquired high-pressure freezer Leica EM ICE for vitrification of bulky biological specimen (up to 200 mm thickness). In addition, the freeze-substitution unit Leica EM AFS2 for resin embedding of the high-pressure frozen samples and the ultramicrotom Leica EM UC7 with the adapter for cryo-ultramicrotomy were purchased in order to provide the facility users with the complete workflow for preparation of thin section samples for both room-temperature electron microscopy and cryo-electron microscopy.
Emerging Topics in Biomolecular Magnetic Resonance – Nick Cox & Kendra Frederick
The series Emerging topics in Biomolecular Magnetic Resonance will continue on July 9th at 16:00 CEST with the following lecturers and topics:
Nick Cox (Australian National University): Spin state evolution during the biological water splitting reaction
Kendra Frederick (UT Southwestern): In cell structural biology enabled by DNP MAS NMR
Emerging Topics in Biomolecular Magnetic Resonance – 4th edition
The series Emerging topics in Biomolecular Magnetic Resonance will continue on June 25th at 16:00 CEST with the following lecturers and topics:
Melinda J. Duer (University of Cambridge): Understanding extracellular matrix disease states with solid-state NMR?
Claudio Luchinat (University of Florence): NMR for metabolomics: again the ‘second best’ technique?
Emerging Topics in Biomolecular Magnetic Resonance – 3rd edition
The series Emerging topics in Biomolecular Magnetic Resonance will continue on June 18th at 16:00 CEST with the following lecturers and topics:
Tuo Wang (Louisiana State University): Elucidation of carbohydrate structure in plant biomass and fungal pathogens using solid-state NMR and DNP methods
Rina Rosenzweig (Weizmann Institute of Science): Molecular Chaperones in Protein Disaggregation - What we can learn from NMR