scholarly journals Structure of the full-length VEGFR-1 extracellular domain in complex with VEGF-A

2017 ◽  
Author(s):  
Sandra Markovic-Mueller ◽  
Edward Stuttfeld ◽  
Mayanka Asthana ◽  
Tobias Weinert ◽  
Spencer Bliven ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Single Particle ◽  
Tyrosine Kinases ◽  
Extracellular Domain ◽  
Receptor Activation ◽  
Full Length ◽  
Lymph Vessel ◽  
X Ray ◽  
X Ray Crystallography ◽  
Single Particle Electron Microscopy

SUMMARYVascular Endothelial Growth Factors (VEGFs) regulate blood and lymph vessel development upon activation of three receptor tyrosine kinases (RTKs), VEGFR-1, −2, and −3. Partial structures of VEGFR/VEGF complexes based on single particle electron microscopy, small angle X-ray scattering, and X-ray crystallography revealed the location of VEGF binding and domain arrangement of individual receptor subdomains. Here we describe the structure of the full-length VEGFR-1 extracellular domain (ECD) in complex with VEGF-A at 4 Å resolution. We combined X-ray crystallography, single particle electron microscopy, and molecular modeling for structure determination and validation. The structure reveals the molecular details of ligand-induced receptor dimerization, in particular of homotypic receptor interactions in Ig-domains 4, 5, and 7. Functional analyses of ligand binding and receptor activation confirm the relevance of these homotypic contacts and identify them as potential therapeutic sites to allosterically inhibit VEGFR-1 activity.

scholarly journals Seeing the insulin receptor in action

2018 ◽  
Vol 217 (5) ◽  
pp. 1555-1555
Author(s):  
Ben Short
Keyword(s):  
Electron Microscopy ◽  
Insulin Receptor ◽  
Single Particle ◽  
Receptor Activation ◽  
Single Particle Electron Microscopy

Researchers use single-particle electron microscopy to visualize an insulin-induced conformational shift that leads to receptor activation.

scholarly journals The Resolution in X-ray Crystallography and Single-Particle Cryogenic Electron Microscopy

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 580
Author(s):  
Victor R.A. Dubach ◽  
Albert Guskov
Keyword(s):  
Electron Microscopy ◽  
Single Particle ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Particle Analysis ◽  
Biological Macromolecules ◽  
Single Particle Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Fourier Transform

X-ray crystallography and single-particle analysis cryogenic electron microscopy are essential techniques for uncovering the three-dimensional structures of biological macromolecules. Both techniques rely on the Fourier transform to calculate experimental maps. However, one of the crucial parameters, resolution, is rather broadly defined. Here, the methods to determine the resolution in X-ray crystallography and single-particle analysis are summarized. In X-ray crystallography, it is becoming increasingly more common to include reflections discarded previously by traditionally used standards, allowing for the inclusion of incomplete and anisotropic reflections into the refinement process. In general, the resolution is the smallest lattice spacing given by Bragg’s law for a particular set of X-ray diffraction intensities; however, typically the resolution is truncated by the user during the data processing based on certain parameters and later it is used during refinement. However, at which resolution to perform such a truncation is not always clear and this makes it very confusing for the novices entering the structural biology field. Furthermore, it is argued that the effective resolution should be also reported as it is a more descriptive measure accounting for anisotropy and incompleteness of the data. In single particle cryo-EM, the situation is not much better, as multiple ways exist to determine the resolution, such as Fourier shell correlation, spectral signal-to-noise ratio and the Fourier neighbor correlation. The most widely accepted is the Fourier shell correlation using a threshold of 0.143 to define the resolution (so-called “gold-standard”), although it is still debated whether this is the correct threshold. Besides, the resolution obtained from the Fourier shell correlation is an estimate of varying resolution across the density map. In reality, the interpretability of the map is more important than the numerical value of the resolution.

scholarly journals Detection of isolated protein-bound metal ions by single-particle cryo-STEM

2017 ◽  
Vol 114 (42) ◽  
pp. 11139-11144 ◽  
Author(s):  
Nadav Elad ◽  
Giuliano Bellapadrona ◽  
Lothar Houben ◽  
Irit Sagi ◽  
Michael Elbaum
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Metal Ions ◽  
Single Particle ◽  
Dark Field ◽  
X Ray ◽  
X Ray Crystallography ◽  
Metal Atoms ◽  
Transmission Electron ◽  
Structural Methods

Metal ions play essential roles in many aspects of biological chemistry. Detecting their presence and location in proteins and cells is important for understanding biological function. Conventional structural methods such as X-ray crystallography and cryo-transmission electron microscopy can identify metal atoms on protein only if the protein structure is solved to atomic resolution. We demonstrate here the detection of isolated atoms of Zn and Fe on ferritin, using cryogenic annular dark-field scanning transmission electron microscopy (cryo-STEM) coupled with single-particle 3D reconstructions. Zn atoms are found in a pattern that matches precisely their location at the ferroxidase sites determined earlier by X-ray crystallography. By contrast, the Fe distribution is smeared along an arc corresponding to the proposed path from the ferroxidase sites to the mineral nucleation sites along the twofold axes. In this case the single-particle reconstruction is interpreted as a probability distribution function based on the average of individual locations. These results establish conditions for detection of isolated metal atoms in the broader context of electron cryo-microscopy and tomography.

scholarly journals Structure Determination by Single-Particle Cryo-Electron Microscopy: Only the Sky (and Intrinsic Disorder) is the Limit

2019 ◽  
Vol 20 (17) ◽  
pp. 4186 ◽  
Author(s):  
Emeka Nwanochie ◽  
Vladimir N. Uversky
Keyword(s):  
Electron Microscopy ◽  
Nmr Spectroscopy ◽  
Structure Determination ◽  
Single Particle ◽  
Protein Structures ◽  
X Ray ◽  
X Ray Crystallography ◽  
Intrinsically Disordered ◽  
Small Proteins ◽  
Cryo Electron Microscopy

Traditionally, X-ray crystallography and NMR spectroscopy represent major workhorses of structural biologists, with the lion share of protein structures reported in protein data bank (PDB) being generated by these powerful techniques. Despite their wide utilization in protein structure determination, these two techniques have logical limitations, with X-ray crystallography being unsuitable for the analysis of highly dynamic structures and with NMR spectroscopy being restricted to the analysis of relatively small proteins. In recent years, we have witnessed an explosive development of the techniques based on Cryo-electron microscopy (Cryo-EM) for structural characterization of biological molecules. In fact, single-particle Cryo-EM is a special niche as it is a technique of choice for the structural analysis of large, structurally heterogeneous, and dynamic complexes. Here, sub-nanometer atomic resolution can be achieved (i.e., resolution below 10 Å) via single-particle imaging of non-crystalline specimens, with accurate 3D reconstruction being generated based on the computational averaging of multiple 2D projection images of the same particle that was frozen rapidly in solution. We provide here a brief overview of single-particle Cryo-EM and show how Cryo-EM has revolutionized structural investigations of membrane proteins. We also show that the presence of intrinsically disordered or flexible regions in a target protein represents one of the major limitations of this promising technique.

scholarly journals On the explicit use of experimental images in high resolution cryo-EM refinement

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 665
Author(s):  
Jacqueline Cherfils ◽  
Jorge Navaza
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Biology ◽  
Single Particle ◽  
Atomic Resolution ◽  
Full Potential ◽  
X Ray ◽  
X Ray Crystallography ◽  
Atomic Models

Single particle cryogenic electron microscopy (cryo-EM) is transforming structural biology by enabling the analysis of difficult macromolecular specimens, such as membrane proteins or large complexes with flexible elements, at near atomic resolution with an accuracy close to that of X-ray crystallography. As the technique continues to improve, it is important to assess and exploit its full potential to produce the most possible reliable atomic models. Here we propose to use the experimental images as the data for refinement and validation, instead of the reconstructed maps as currently used. This procedure, which is in spirit quite similar to that used in X-ray crystallography where the data include experimental phases, should contribute to improve the quality of the cryo-EM atomic models.

scholarly journals On the explicit use of experimental images in high resolution cryo-EM refinement

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 665
Author(s):  
Jacqueline Cherfils ◽  
Jorge Navaza
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Membrane Proteins ◽  
Structural Biology ◽  
Single Particle ◽  
Atomic Resolution ◽  
Full Potential ◽  
X Ray ◽  
X Ray Crystallography

Single particle cryogenic electron microscopy (cryo-EM) is transforming structural biology by enabling the analysis of difficult macromolecular specimens, such as membrane proteins or large complexes with flexible elements, at near atomic resolution with an accuracy close to that of X-ray crystallography. As the technique continues to improve, it is important to assess and exploit its full potential to produce the most possible reliable atomic models. Here we propose to use the experimental images as the data for refinement and validation, instead of the reconstructed maps as currently used. This procedure, which is in spirit quite similar to that used in X-ray crystallography where the data include experimental phases, should contribute to improve the quality of the models.

scholarly journals qFit 3: Protein and ligand multiconformer modeling for X-ray crystallographic and single-particle cryo-EM density maps

2020 ◽  
Author(s):  
Blake T. Riley ◽  
Stephanie A. Wankowicz ◽  
Saulo H. P. de Oliveira ◽  
Gydo C. P. van Zundert ◽  
Daniel Hogan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Single Particle ◽  
Structural Data ◽  
Conformational Ensemble ◽  
Distributed Application ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Formidable Challenge ◽  
Density Maps

AbstractNew X-ray crystallography and cryo-electron microscopy (cryo-EM) approaches yield vast amounts of structural data from dynamic proteins and their complexes. Modeling the full conformational ensemble can provide important biological insights, but identifying and modeling an internally consistent set of alternate conformations remains a formidable challenge. qFit efficiently automates this process by generating a parsimonious multiconformer model. We refactored qFit from a distributed application into software that runs efficiently on a small server, desktop, or laptop. We describe the new qFit 3 software and provide some examples. qFit 3 is open-source under the MIT license, and is available at https://github.com/ExcitedStates/qfit-3.0.

Sign in / Sign up

Export Citation Format

Share Document