|Entry||Database: EMDB / ID: 4419|
|Title||Representative tomogram of mature MLV particles|
|Map data||Representative tomogram of mature MLV particles for subtomogram averaging|
|Sample||Murine leukemia virus:|
|Source||Murine leukemia virus|
|Method||electron tomography / cryo EM|
|Authors||Qu K / Glass B / Dolezal M / Schur FKM / Rein A / Rumlova M / Ruml T / Kraeusslich HG / Briggs JAG|
|Citation||Journal: Proc. Natl. Acad. Sci. U.S.A. / Year: 2018|
Title: Structure and architecture of immature and mature murine leukemia virus capsids.
Authors: Kun Qu / Bärbel Glass / Michal Doležal / Florian K M Schur / Brice Murciano / Alan Rein / Michaela Rumlová / Tomáš Ruml / Hans-Georg Kräusslich / John A G Briggs
Abstract: Retroviruses assemble and bud from infected cells in an immature form and require proteolytic maturation for infectivity. The CA (capsid) domains of the Gag polyproteins assemble a protein lattice as ...Retroviruses assemble and bud from infected cells in an immature form and require proteolytic maturation for infectivity. The CA (capsid) domains of the Gag polyproteins assemble a protein lattice as a truncated sphere in the immature virion. Proteolytic cleavage of Gag induces dramatic structural rearrangements; a subset of cleaved CA subsequently assembles into the mature core, whose architecture varies among retroviruses. Murine leukemia virus (MLV) is the prototypical γ-retrovirus and serves as the basis of retroviral vectors, but the structure of the MLV CA layer is unknown. Here we have combined X-ray crystallography with cryoelectron tomography to determine the structures of immature and mature MLV CA layers within authentic viral particles. This reveals the structural changes associated with maturation, and, by comparison with HIV-1, uncovers conserved and variable features. In contrast to HIV-1, most MLV CA is used for assembly of the mature core, which adopts variable, multilayered morphologies and does not form a closed structure. Unlike in HIV-1, there is similarity between protein-protein interfaces in the immature MLV CA layer and those in the mature CA layer, and structural maturation of MLV could be achieved through domain rotations that largely maintain hexameric interactions. Nevertheless, the dramatic architectural change on maturation indicates that extensive disassembly and reassembly are required for mature core growth. The core morphology suggests that wrapping of the genome in CA sheets may be sufficient to protect the MLV ribonucleoprotein during cell entry.
|Date||Deposition: Nov 14, 2018 / Header (metadata) release: Dec 5, 2018 / Map release: Dec 5, 2018 / Last update: Dec 19, 2018|
Downloads & links
|File||emd_4419.map.gz (map file in CCP4 format, 4129231 KB)|
|Projections & slices|
Images are generated by Spider.
|Voxel size||X=Y=Z: 2.7 Å|
CCP4 map header:
-Entire Murine leukemia virus
|Entire||Name: Murine leukemia virus / Number of components: 1|
-Component #1: virus, Murine leukemia virus
|Virus||Name: Murine leukemia virus / Class: VIRION / Empty: No / Enveloped: Yes / Isolate: STRAIN|
|Species||Species: Murine leukemia virus|
|Source (engineered)||Expression System: Homo sapiens (human) / Vector: M2204 / Cell of expression system: HEK 293T|
|Specimen||Specimen state: particle / Method: cryo EM|
|Sample solution||pH: 6|
|Vitrification||Instrument: FEI VITROBOT MARK II / Cryogen name: ETHANE / Temperature: 288 K / Humidity: 95 %|
-Electron microscopy imaging
Model: Titan Krios / Image courtesy: FEI Company
|Imaging||Microscope: FEI TITAN KRIOS|
|Electron gun||Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Electron dose: 1.8 e/Å2 / Illumination mode: FLOOD BEAM|
|Lens||Magnification: 105000.0 X (nominal) / Cs: 2.7 mm / Imaging mode: BRIGHT FIELD / Defocus: 2000.0 - 7500.0 nm / Energy filter: GIF Quantum LS|
|Specimen Holder||Model: FEI TITAN KRIOS AUTOGRID HOLDER|
|Camera||Detector: GATAN K2 QUANTUM (4k x 4k)|
|Image acquisition||Sampling size: 5 microns|
Details: Dose fluctuation was caused by the ring collapse of FEG during data collection.
|Processing||Method: electron tomography / Number of sections: 45|
|3D reconstruction||Software: eTomo|
-Atomic model buiding
|Modeling #1||Refinement space: REAL|
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