Structure of dynein-dynactin on microtubules shows tandem recruitment of cargo adaptors

Cytoplasmic dynein is a microtubule motor that is activated by its cofactor dynactin and a coiled-coil cargo adaptor. There is currently limited structural information on how the resulting complex interacts with microtubules and how adaptors are recruited. Here, we develop a cryo-EM processing pipeline to solve the high-resolution structure of dynein-dynactin and the adaptor BICDR1 bound to microtubules. This reveals the asymmetric interactions between neighbouring dynein motor domains and how it relates to their motile behaviour. We find unexpectedly that two adaptors occupy the complex. Both adaptors make similar interactions with the dyneins but diverge in their contacts with each other and dynactin. Our structure has implications for the stability and stoichiometry of motor recruitment by cargos.