Direct visualization of vaults within intact cells by electron cryo-tomography
The vault complex is the largest cellular ribonucleoprotein complex ever characterized and is present across diverse Eukarya. Despite significant information regarding the structure, composition and evolutionary conservation of the vault, little is know about the complex’s actual biological function. To determine if intracellular vaults are morphologically similar to previously studied purified and recombinant vaults, we have used electron cryo-tomography to characterize the vault complexes found in the thin edges of primary human cells growing in tissue culture. Our studies confirm that intracellular vaults are similar in overall size and shape to purified and recombinant vaults previously analyzed. Results from subtomogram averaging indicate that densities within the vault lumen are not ordered, but randomly distributed. We also observe that vaults located in the extreme periphery of the cytoplasm predominately associate with granule-like structures and actin. Our ultrastructure studies augment existing biochemical, structural and genetic information on the vault, and provide important intracellular context for the ongoing efforts to understand the biological function of the native cytoplasmic vault.
KeywordsVault Ribonucleoprotein complex Granules RNA Electron cryo-tomography
Supplementary material 1 (MOV 2069 kb)
- 8.Casanas A, Querol-Audi J, Guerra P, Pous J, Tanaka H, Tsukihara T, Verdaguer N, Fita I (2013) New features of vault architecture and dynamics revealed by novel refinement using the deformable elastic network approach. Acta Crystallogr D Biol Crystallogr 69(Pt 6):1054–1061. doi:10.1107/S0907444913004472 PubMedCrossRefGoogle Scholar
- 14.Dortet L, Mostowy S, Samba-Louaka A, Louaka AS, Gouin E, Nahori M-A, Wiemer EAC, Dussurget O, Cossart P (2011) Recruitment of the major vault protein by InlK: a Listeria monocytogenes strategy to avoid autophagy. PLoS Pathog 7(8):e1002168. doi:10.1371/journal.ppat.1002168 PubMedCentralPubMedCrossRefGoogle Scholar