Structure of the dynein-2 complex and its assembly with intraflagellar transport trains

Dynein-2 assembles with polymeric intraflagellar transport (IFT) trains to form a transport machinery crucial for cilia biogenesis and signaling. Here we recombinantly expressed the ~1.4 MDa human dynein-2 complex and solved its cryo-EM structure to near-atomic resolution. The two identical copies of the dynein-2 heavy chain are contorted into different conformations by a WDR60-WDR34 heterodimer and a block of two RB and six LC8 light chains. One heavy chain is steered into a zig-zag, which matches the periodicity of the anterograde IFT-B train. Contacts between adjacent dyneins along the train indicate a cooperative mode of assembly. Removal of the WDR60-WDR34-light chain subcomplex renders dynein-2 monomeric and relieves auto-inhibition of its motility. Our results converge on a model in which an unusual stoichiometry of non-motor subunits control dynein-2 assembly, asymmetry, and activity, giving mechanistic insight into dynein-2’s interaction with IFT trains and the origin of diverse functions in the dynein family.