LAUSR

Cytoskeletal motor protein motility requires coordination of ATPase and filament-binding cycles. Mechanical tension strongly influences these processes, and likely regulates motor stepping as external forces resist motor movement and intramolecular tension develops between motor domains. In cytoplasmic dynein, an AAA+ ATPase, applied tension affects microtubule (MT)-binding strength anisotropically -backward tension induces stronger binding- while in the absence of tension, reconfiguration of the coiled-coil ‘stalk’ (which connects the AAA+ and MT-binding domains) is known to alter MT affinity. Using optical tweezers, mutagenesis, and chemical cross-linking, we show that preventing relative motion of the stalk helices or deleting the ‘strut’ (which emerges from the AAA+ domain and contacts the stalk) both eliminate tension-based regulation of MT-binding strength. Thus, tension alters dynein's MT-binding strength by inducing sliding of the stalk helices, and the strut is a key mediator of this process.