Cryo-electron tomography: 3-dimensional imaging of soft matter

Fabio Nudelman; Gijsbertus de With; Nico A. J. M. Sommerdijk

doi:10.1039/c0sm00441c

Cryo-electron tomography reveals that dynactin recruits a team of dyneins for processive motility

10.1101/182576 ◽

2017 ◽

Cited By ~ 1

Author(s):

Danielle A. Grotjahn ◽

Saikat Chowdhury ◽

Yiru Xu ◽

Richard J. McKenney ◽

Trina A. Schroer ◽

...

Keyword(s):

Structural Information ◽

Electron Tomography ◽

Force Production ◽

Cytoplasmic Dynein ◽

Dimensional Structure ◽

Cellular Transport ◽

3 Dimensional ◽

Dynein Motor ◽

Cryo Electron Tomography ◽

Dynactin Complex

AbstractA key player in the intracellular trafficking network is cytoplasmic dynein, a protein complex that transports molecular cargo along microtubule tracks. It has been shown that vertebrate dynein’s movement becomes strikingly enhanced upon interacting with a cofactor named dynactin and one of several cargo-adapters, such as BicaudalD2. However, the mechanisms responsible for this increase in transport efficiency are not well understood, largely due to a lack of structural information. We used cryo-electron tomography to visualize the first 3-dimensional structure of the intact dynein-dynactin complex bound to microtubules. Our structure reveals that the dynactin-cargo-adapter complex recruits and binds to two dimeric cytoplasmic dyneins. Interestingly, the dynein motor organization closely resembles that of axonemal dynein, suggesting that cytoplasmic dynein and axonemal dyneins may utilize similar mechanisms to coordinate multiple motors. We propose that grouping dyneins onto a single dynactin scaffold promotes collective force production as well as unidirectional processive motility. These findings provide a structural platform that facilitates a deeper biochemical and biophysical understanding of dynein regulation and cellular transport.

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The platelet interior revisited: electron tomography reveals tubular α-granule subtypes

Blood ◽

10.1182/blood-2010-02-268680 ◽

2010 ◽

Vol 116 (7) ◽

pp. 1147-1156 ◽

Cited By ~ 117

Author(s):

Hezder van Nispen tot Pannerden ◽

Felix de Haas ◽

Willie Geerts ◽

George Posthuma ◽

Suzanne van Dijk ◽

...

Keyword(s):

Von Willebrand Factor ◽

Electron Tomography ◽

Human Platelets ◽

Membrane Organization ◽

3 Dimensional ◽

Cryo Electron Tomography ◽

Large Heterogeneity ◽

Membrane Bound ◽

Von Willebrand ◽

Willebrand Factor

Abstract We have used (cryo) electron tomography to provide a 3-dimensional (3D) map of the intracellular membrane organization of human platelets at high spatial resolution. Our study shows that the open canalicular system and dense tubular system are highly intertwined and form close associations in specialized membrane regions. 3D reconstructions of individual α-granules revealed large heterogeneity in their membrane organization. On the basis of their divergent morphology, we categorized α-granules into the following subtypes: spherical granules with electron-dense and electron-lucent zone containing 12-nm von Willebrand factor tubules, subtypes containing a multitude of luminal vesicles, 50-nm-wide tubular organelles, and a population with 18.4-nm crystalline cross-striations. Low-dose (cryo) electron tomography and 3D reconstruction of whole vitrified platelets confirmed the existence of long tubular granules with a remarkably curved architecture. Immunoelectron microscopy confirmed that these extended structures represent α-granule subtypes. Tubular α-granules represent approximately 16% of the total α-granule population and are detected in approximately half of the platelet population. They express membrane-bound proteins GLUT3 and αIIb-β3 integrin and contain abundant fibrinogen and albumin but low levels of β-thromboglobulin and no von Willebrand factor. Our 3D study demonstrates that, besides the existence of morphologically different α-granule subtypes, high spatial segregation of cargo exists within individual α-granules.

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