Cryo-electron tomography of vaccinia virus.
The combination of cryo-microscopy and electron tomographic reconstruction has allowed us to determine the structure of one of the more complex viruses, intracellular mature vaccinia virus, at a resolution of 4-6 nm. The tomographic reconstruction allows us to dissect the different structural components of the viral particle, avoiding projection artifacts derived from previous microscopic observations. A surface-rendering representation revealed brick-shaped viral particles with slightly rounded edges and dimensions of approximately 360 x 270 x 250 nm. The outer layer was consistent with a lipid membrane (5-6 nm thick), below which usually two lateral bodies were found, built up by a heterogeneous material without apparent ordering or repetitive features. The internal core presented an inner cavity with electron dense coils of presumptive DNA-protein complexes, together with areas of very low density. The core was surrounded by two layers comprising an overall thickness of approximately 18-19 nm; the inner layer was consistent with a lipid membrane. The outer layer was discontinuous, formed by a periodic palisade built by the side interaction of T-shaped protein spikes that were anchored in the lower membrane and were arranged into small hexagonal crystallites. It was possible to detect a few pore-like structures that communicated the inner side of the core with the region outside the layer built by the T-shaped spike palisade.
Cyrklaff
Marek
M
Max Planck Institute of Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried, Germany.
Risco
Cristina
C
Fernández
Jose Jesús
JJ
Jiménez
Maria Victoria
MV
Estéban
Mariano
M
Baumeister
Wolfgang
W
Carrascosa
José L
JL
D020285:Cryoelectron Microscopy; D014054:Tomography; D014616:Vaccinia virus / Q000648:ultrastructure*