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Transmission Electron Microscopes

Krios G3i Cryo-TEM for Life Sciences

Unravelling ‘Life’ at the Molecular Level – Easier, Faster, and more Reliably 

The new Thermo Scientific™ Krios™ G3i Cryo Transmission Electron Microscope (Cryo-TEM) enables life science researchers to unravel life at the molecular level—easier, faster, and more reliably than ever before. Its highly stable 300 kV TEM platform and industry-leading Autoloader (cryogenic sample manipulation robot) are designed for automated applications, such as single particle analysis (SPA) and cryo-tomography. Designed-in connectivity ensures a robust and risk-free pathway throughout the entire workflow, from sample preparation and optimization to image acquisition and data processing.

Setting up data acquisition has been made easier and quicker by enhanced automation and systematic user guidance. This allows every user to achieve the ultimate performance for every experiment. Simultaneously, the high-resolution performance and throughput of the Krios G3i Cryo-TEM have been further improved by cleverly combining hardware improvements with advanced software capabilities.





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Key Benefits

Enhanced ease of use through automation

The Krios G3i Cryo-TEM reduces the number of complex alignments that a user has to perform. For recurring alignments that need to be done regularly, automated alignment routines have been implemented into the EPU software for SPA. Furthermore the EPU user interface has been further streamlined to provide comprehensive user guidance.

Reproducible, optimal tool performance always guarantee

The optimal thermal and mechanical stability of the Krios G3i Cryo-TEM ensure perfect optical performance. The instrument features a self-assessment function that automatically evaluates the optical status of the microscope, providing feedback for any steps that require optimization. Additionally, automated alignment routines allow the instrument to be tuned to its optimal starting point for SPA or tomography experiments.

Maximum Throughput

EPU is the native software package for SPA automated screening and acquisition of large data sets on the Thermo Fisher cryo-TEMs. With full control of the Autoloader from within EPU, all grids in a cassette can be batch-screened: after the creation of a grid atlas, ice quality (presence, thickness) of the vitrified grids is automatically categorized to support guided selection of grid squares.

High resolution performance

The Krios Cryo-TEM has a proven track record of high resolution imaging of a wide variety of particles: the vast majority of published structures at or below 4 Å have been determined using Thermo Fisher cryo-TEMs . Constant power lenses reduce thermal drift, and contribute to the excellent system stability during long automated acquisition sessions. To allow imaging of increasingly smaller particles at increasingly higher resolution, the Krios G3i comes with Volta Phase Plate integration and a guaranteed <1% anisotropic magnification distortion.

Workflow connectivity

For successful cryo-EM data acquisition, optimization of both biochemistry and vitrification requires an efficient screening process. The Krios G3i Cryo-TEM can be integrated in a SPA workflow to where samples will be evaluated and optimized using the Talos Arctica or Glacios Cryo-TEMs, before imaging them at high-resolution in the Krios G3i Cryo-TEM

The designed-in connectivity of the Autoloader capsule and cassette systems ensure a robust and contamination-free transfer of samples between Glacios, Arctica and Krios Cryo-TEMs, without the need for manipulation of individual small grids.

Featured Document

Krios G3i Cryo-TEM Datasheet

Our newest Cryo-TEM enables life science researchers to unravel life at the molecular level. Its highly stable 300 kV TEM platform and industry-leading Autoloader (cryogenic sample manipulation robot) are designed for automated applications, such as single particle analysis (SPA) and cryo-tomography. Designed-in connectivity ensures a robust and risk-free pathway throughout the entire workflow, from sample preparation and optimization to image acquisition and data processing.

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Featured Document

Titan Krios TEM Publications

List of published articles and research results with the Titan Krios

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Featured News

Congratulations to the winners of the 2017 Nobel Prize in Chemistry.

Three scientists; Dr. Jacques Dubochet Dr. Joachim Frank, and Dr. Richard Henderson, were awarded the prize for their developments within Cryo-Electron Microscopy.

We are extremely proud of what these researchers and the structural biology community have achieved.

Publication list for Titan Krios for Life Sciences

1.
A. Heuer, M. Gerovac, C. Schmidt, S. Trowitzsch, A. Preis, P. Kötter, O. Berninghausen, T. Becker, R. Beckmann, R. Tampé   (2017)   Structure of the 40S-ABCE1 post-splitting complex in ribosome recycling and translation initiation.   Nature structural & molecular biology   

DOI:  10.1038/nsmb.3396

References PDB protein(s):  5LL6

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Structure of the 40S-ABCE1 post-splitting complex in ribosome recycling and translation initiation.

A. Heuer, M. Gerovac, C. Schmidt, S. Trowitzsch, A. Preis, P. Kötter, O. Berninghausen, T. Becker, R. Beckmann, R. Tampé

The essential ATP-binding cassette protein ABCE1 splits 80S ribosomes into 60S and 40S subunits after canonical termination or quality-control-based mRNA surveillance processes. However, the underlying splitting mechanism remains enigmatic. Here, we present a cryo-EM structure of the yeast 40S-ABCE1 post-splitting complex at 3.9-Å resolution. Compared to the pre-splitting state, we observe repositioning of ABCE1's iron-sulfur cluster domain, which rotates 150° into a binding pocket on the 40S subunit. This repositioning explains a newly observed anti-association activity of ABCE1. Notably, the movement implies a collision with A-site factors, thus explaining the splitting mechanism. Disruption of key interactions in the post-splitting complex impairs cellular homeostasis. Additionally, the structure of a native post-splitting complex reveals ABCE1 to be part of the 43S initiation complex, suggesting a coordination of termination, recycling, and initiation.

2.
K. Škubník, J. Nováček, T. Füzik, A. Přidal, R. Paxton, P. Plevka   (2017)   Structure of deformed wing virus, a major honey bee pathogen.   Proceedings of the National Academy of Sciences of the United States of America   114

DOI:  10.1073/pnas.1615695114

References PDB protein(s):  5L7Q, 5L8Q, 5MUP, 5MV5, 5MV6

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Structure of deformed wing virus, a major honey bee pathogen.

K. Škubník, J. Nováček, T. Füzik, A. Přidal, R. Paxton, P. Plevka

The worldwide population of western honey bees (Apis mellifera) is under pressure from habitat loss, environmental stress, and pathogens, particularly viruses that cause lethal epidemics. Deformed wing virus (DWV) from the family Iflaviridae, together with its vector, the mite Varroa destructor, is likely the major threat to the world's honey bees. However, lack of knowledge of the atomic structures of iflaviruses has hindered the development of effective treatments against them. Here, we present the virion structures of DWV determined to a resolution of 3.1 Å using cryo-electron microscopy and 3.8 Å by X-ray crystallography. The C-terminal extension of capsid protein VP3 folds into a globular protruding (P) domain, exposed on the virion surface. The P domain contains an Asp-His-Ser catalytic triad that is, together with five residues that are spatially close, conserved among iflaviruses. These residues may participate in receptor binding or provide the protease, lipase, or esterase activity required for entry of the virus into a host cell. Furthermore, nucleotides of the DWV RNA genome interact with VP3 subunits. The capsid protein residues involved in the RNA binding are conserved among honey bee iflaviruses, suggesting a putative role of the genome in stabilizing the virion or facilitating capsid assembly. Identifying the RNA-binding and putative catalytic sites within the DWV virion structure enables future analyses of how DWV and other iflaviruses infect insect cells and also opens up possibilities for the development of antiviral treatments.

3.
C. Engel, T. Gubbey, S. Neyer, S. Sainsbury, C. Oberthuer, C. Baejen, C. Bernecky, P. Cramer   (2017)   Structural Basis of RNA Polymerase I Transcription Initiation.   Cell   169

DOI:  10.1016/j.cell.2017.03.003

References PDB protein(s):  5N5Y, 5N5Z, 5N60, 5N61

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Structural Basis of RNA Polymerase I Transcription Initiation.

C. Engel, T. Gubbey, S. Neyer, S. Sainsbury, C. Oberthuer, C. Baejen, C. Bernecky, P. Cramer

Transcription initiation at the ribosomal RNA promoter requires RNA polymerase (Pol) I and the initiation factors Rrn3 and core factor (CF). Here, we combine X-ray crystallography and cryo-electron microscopy (cryo-EM) to obtain a molecular model for basal Pol I initiation. The three-subunit CF binds upstream promoter DNA, docks to the Pol I-Rrn3 complex, and loads DNA into the expanded active center cleft of the polymerase. DNA unwinding between the Pol I protrusion and clamp domains enables cleft contraction, resulting in an active Pol I conformation and RNA synthesis. Comparison with the Pol II system suggests that promoter specificity relies on a distinct "bendability" and "meltability" of the promoter sequence that enables contacts between initiation factors, DNA, and polymerase.

4.
J. Gu, M. Wu, R. Guo, K. Yan, J. Lei, N. Gao, M. Yang   (2016)   The architecture of the mammalian respirasome.   Nature   537

DOI:  10.1038/nature19359

References PDB protein(s):  5GPN

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The architecture of the mammalian respirasome.

J. Gu, M. Wu, R. Guo, K. Yan, J. Lei, N. Gao, M. Yang

The respiratory chain complexes I, III and IV (CI, CIII and CIV) are present in the bacterial membrane or the inner mitochondrial membrane and have a role of transferring electrons and establishing the proton gradient for ATP synthesis by complex V. The respiratory chain complexes can assemble into supercomplexes (SCs), but their precise arrangement is unknown. Here we report a 5.4 Å cryo-electron microscopy structure of the major 1.7 megadalton SCI1III2IV1 respirasome purified from porcine heart. The CIII dimer and CIV bind at the same side of the L-shaped CI, with their transmembrane domains essentially aligned to form a transmembrane disk. Compared to free CI, the CI in the respirasome is more compact because of interactions with CIII and CIV. The NDUFA11 and NDUFB9 supernumerary subunits of CI contribute to the oligomerization of CI and CIII. The structure of the respirasome provides information on the precise arrangements of the respiratory chain complexes in mitochondria.