57 research outputs found
Structure of hibernating ribosomes studied by cryoelectron tomography in vitro and in situ
CryoET shows the configuration of the ephemeral translationally inactive 100S ribosomal dimer
Geometric analysis of macromolecule organization within cryo-electron tomograms
Cryo-electron tomography (CET) provides unprecedented views into the native cellular environment at molecular resolution. While subtomogram analysis yields high-resolution native structures of molecular complexes, it also determines the precise positions and orientations of these macromolecules within the cell. Analyzing the geometric relationships between adjacent macromolecules can offer structural insights into molecular interactions and identify supramolecular ensembles. However, computation..
Electron cryotomography: a new view into microbial ultrastructure
Electron cryotomography (ECT) is an emerging technology that allows thin samples such as small bacterial cells to be imaged in 3D in a nearly native state to âmolecularâ (not, vert, similar4 nm) resolution. As such, ECT is beginning to deliver long-awaited insight into the positions and structures of cytoskeletal filaments, cell wall elements, motility machines, chemoreceptor arrays, internal compartments, and other ultrastructures. Here we briefly explain ECT, review its recent contributions to microbiology, and conclude with a discussion of future prospects
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Ribosome-associated vesicles: A dynamic subcompartment of the endoplasmic reticulum in secretory cells
The endoplasmic reticulum (ER) is a highly dynamic network of membranes. Here, we combine live-cell microscopy with in situ cryoâelectron tomography to directly visualize ER dynamics in several secretory cell types including pancreatic ÎČ-cells and neurons under near-native conditions. Using these imaging approaches, we identify a novel, mobile form of ER, ribosome-associated vesicles (RAVs), found primarily in the cell periphery, which is conserved across different cell types and species. We show that RAVs exist as distinct, highly dynamic structures separate from the intact ER reticular architecture that interact with mitochondria via direct intermembrane contacts. These findings describe a new ER subcompartment within cells
Integrative modelling of cellular assemblies
A wide variety of experimental techniques can be used for understanding the precise molecular mechanisms underlying the activities of cellular assemblies. The inherent limitations of a single experimental technique often requires integration of data from complementary approaches to gain sufficient insights into the assembly structure and function. Here, we review popular computational approaches for integrative modelling of cellular assemblies, including protein complexes and genomic assemblies. We provide recent examples of integrative models generated for such assemblies by different experimental techniques, especially including data from 3D electron microscopy (3D-EM) and chromosome conformation capture experiments, respectively. We highlight general concepts in integrative modelling and discuss the need for careful formulation and merging of different types of information
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