New Study Provides First 3D Visualization of Dynein-Dynactin Complex Bound to Microtubules

On the cellular highway, motor proteins called dyneins rule the road. Dyneins "walk" along structures called microtubules to deliver cellular cargo, such as signaling molecules and organelles, to different parts of a cell. Without dynein on the job, cells cannot divide and people can develop neurological diseases. Now, a new study, which was published on February 7, 2018 in Nature Structural & Molecular Biology, provides the first three-dimensional (3D) visualization of the dynein-dynactin complex bound to microtubules. The article is titled “Cryo-Electron Tomography Reveals That Dynactin Recruits a Team of Dyneins for Processive Motility.” The study leaders from The Scripps Research Institute (TSRI) report that a protein called dynactin hitches two dyneins together, like a yoke locking together a pair of draft horses. "If you want a team of horses to move in one direction, you need to line them up," says Gabriel C. Lander, PhD, a TSRI Associate Professor and senior author of the study. "That's exactly what dynactin is doing to dynein molecules." Understanding how the dynein-dynactin complex is assembled and organized provides a critical foundation to explain the underlying causes of several dynein-related neurodegenerative diseases such as spinal muscular atrophy (SMA) and Charcot-Marie-Tooth (CMT) disease. Researchers knew that dynactin is required for dynein to move cargo, but they struggled to get a complete picture of how the different parts of the complex worked together. "We knew that dynein only becomes active when it binds with a partner called dynactin. The problem was that, historically, it was difficult to solve this structure because it is very flexible and dynamic," explains Danielle Grotjahn, a TSRI graduate student and co-first author of the study.
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