Insights into LIS1 function in cargo-adapter-mediated dynein activation in vivo

Deficiency of the LIS1 protein causes lissencephaly, a brain developmental disorder. Although LIS1 binds the microtubule motor cytoplasmic dynein and has been linked to dynein function in many experimental systems, its mechanism of action remains unclear. Here we revealed the function of LIS1 in cargo-adapter-mediated dynein activation in the model organism Aspergillus nidulans . Specifically, we found that overexpressed cargo adapter HookA (Hook in A. nidulans ) missing its cargo-binding domain (ΔC-HookA) causes dynein and its regulator dynactin to relocate from the microtubule plus ends to the minus ends, and this dramatic relocation requires LIS1 and its binding protein NudE. Astonishingly, the requirement for LIS1 or NudE can be bypassed to a significant extent by specific mutations that open the auto-inhibited “phi-dynein” in which the motor domains of the dynein dimer are held close together. Our results suggest a novel mechanism of LIS1 action: it promotes the switch of dynein from the auto-inhibited state to an open state to facilitate dynein activation. Summary This study reveals the role of Lissencephaly 1 (LIS1) in cargo-adapter-mediated dynein activation. Furthermore, it discovers a novel mechanism of LIS1 action involving a switch of dynein from an auto-inhibited state to an active state.