Cryo-EM Reveals How Human Cytoplasmic Dynein Is Auto-inhibited and Activated

Summary

Cytoplasmic dynein-1 binds dynactin and cargo adaptor proteins to form a transport machine capable of long-distance processive movement along microtubules. However, it is unclear why dynein-1 moves poorly on its own or how it is activated by dynactin. Here, we present a cryoelectron microscopy structure of the complete 1.4-megadalton human dynein-1 complex in an inhibited state known as the phi-particle. We reveal the 3D structure of the cargo binding dynein tail and show how self-dimerization of the motor domains locks them in a conformation with low microtubule affinity. Disrupting motor dimerization with structure-based mutagenesis drives dynein-1 into an open form with higher affinity for both microtubules and dynactin. We find the open form is also inhibited for movement and that dynactin relieves this by reorienting the motor domains to interact correctly with microtubules. Our model explains how dynactin binding to the dynein-1 tail directly stimulates its motor activity.

Graphical Abstract

Highlights

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  Cryo-EM shows human cytoplasmic dynein-1 in its auto-inhibited, phi-particle form

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  Phi-particle disruption in vitro and in cells reveals its role in dynein regulation

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  There is a transition from phi-particle to open-dynein: both forms are inhibited

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  Dynactin binds open-dynein and aligns its motors to activate processive movement

Abstract

Cryo-EM of human cytoplasmic dynein-1 reveals the mechanism underlying its auto-inhibition and activation.