Conserved roles for the dynein intermediate chain and Ndel1 in assembly and activation of dynein

Processive transport by the microtubule motor cytoplasmic dynein requires the regulated assembly of a dynein-dynactin-adapter complex. Interactions between dynein and dynactin were initially ascribed to the dynein intermediate chain N-terminus and the dynactin subunit p150Glued. However, recent cryo-EM structures have not resolved this interaction, questioning its importance. The intermediate chain also interacts with Nde1/Ndel1, which compete with p150Glued for binding. We reveal that the intermediate chain N-terminus is a critical evolutionarily conserved hub that interacts with dynactin and Ndel1, the latter of which recruits LIS1 to drive complex assembly. In additon to revealing that the intermediate chain N-terminus is likely bound to p150Glued in active transport complexes, our data support a model whereby Ndel1-LIS1 must dissociate prior to LIS1 being handed off to dynein in temporally discrete steps. Our work reveals previously unknown steps in the dynein activation pathway, and provide insight into the integrated activities of LIS1/Ndel1 and dynactin/cargo-adapters. The mechanism by which dynein-mediated cargo transport is switched on is unresolved. This study reveals insights into the roles of the human disease genes Ndel1 and LIS1 in the assembly and activation of dynein transport complexes.

Automated summary

This study reveals previously unknown steps in the activation pathway of cytoplasmic dynein-mediated cargo transport and provides insight into the integrated activities of LIS1/Ndel1 and dynactin/cargo-adapters. The findings contribute to the understanding of the roles of the human disease genes Ndel1 and LIS1 in the assembly and activation of dynein transport complexes.