Self-Regulation of Cytoplasmic Dynein through its Unconventional Force Response

Abstract

Cytoplasmic dynein is essential for a wide range of cellular activities, including intracellular transport, cell division, and cell migration in most of eukaryotic organisms. To achieve these various functions, dynein activity must be tightly controlled. However, the motility of mammalian cytoplasmic dynein has been controversial in previous studies, which makes it unclear how dynein activity is regulated and tuned for a specific function. Here, using electron microscopy and DNA nanostructure-based motility assays, we investigated how the control of dynein activity is achieved. We showed that single dynein molecules diffused along microtubules in an autoinhibited state, in which two motor heads were stacked together. This state was released when multiple dynein molecules worked together on a single cargo or when dynein was pulled by an optical tweezer, suggesting that individual dynein molecules in the team were activated through destabilization of the stacked conformation by mechanical strain generated between dynein molecules. We confirmed this force-dependent activation mechanism by observing the movement of a chimeric dynein fused with a inactive kinesin, which we assume acts as a load. This mechanism would function at a fundamental level of dynein regulation that does not require an external regulator, thereby serving as a stable basis for the higher-level regulation of dynein-driven transport.