Exploiting cryo-EM structures of actomyosin-5a to reveal the physical properties of its lever

Abstract

AbstractMyosin 5a transports cellular cargos along actin filaments towards the cell periphery. Its long lever plays a key role in determining the large size of its powerstoke, stepping distance along F-actin, ability to bear load and its regulation by Ca2+. Despite this, little is known about the physical properties of the lever and how they contribute to the mechanics of walking. Using a combination of cryo-electron microscopy and molecular dynamics simulations, we resolved the first structure of myosin 5a comprising the motor domain and full-length lever (subfragment-1) bound to actin. From the flexibility captured in the cryo-electron microscopy data, we were able to characterise the stiffness of the lever. Here, we demonstrate how the structure and flexibility of the lever contribute to the regulation and walking behaviour of myosin 5a.