Chaperone-enhanced purification of unconventional myosin 15, a molecular motor specialized for stereocilia protein trafficking

Significance Mutations in unconventional myosin 15 cause nonsyndromic autosomal recessive deafness, a common form of hereditary hearing loss in humans. Myosin 15 is required for the development of hair cell mechanosensory stereocilia that detect sounds within the inner ear. To our knowledge, our work offers the first insight into the biophysical properties of purified myosin 15. Using ensemble and single molecule techniques, we show that myosin 15 is a high-duty ratio motor, which is a characteristic of myosins that can move processively along actin filaments. We also introduce a new strategy for producing myosins by chaperone coexpression inSpodoptera frugiperda insect cells. This approach may help optimize expression of skeletal and cardiac muscle myosins, which are emerging as translational drug targets but are presently refractory to larger-scale purification.