Cryo-EM captures early intermediate steps in dynein activation by LIS1

Cytoplasmic dynein-1 (dynein) is an essential molecular motor in eukaryotic cells. Dynein primarily exists in an autoinhibited Phi state and requires conformational changes to assemble with its cofactors and form active transport complexes. LIS1, a key dynein regulator, enhances dynein activation and assembly. Using cryo-EM and a human dynein-LIS1 sample incubated with ATP, we map the conformational landscape of dynein activation by LIS1 and identify an early intermediate state that we propose precedes the previously identified dynein-LIS1 Chi state. Mutations that disrupt this species, which we termed "Pre-Chi", lead to motility defects in vitro, emphasizing its functional importance. Together, our findings provide insights into how LIS1 relieves dynein autoinhibition during the activation pathway.