Cardiolipin membranes drive Myosin VI activation, oligomerization, and processive cargo transport

Mitochondrial damage determines cell fate, leading to mitochondrial autophagy or cellular apoptosis in health and disease. The molecular mechanisms and role of the acto-myosin cytoskeleton regulating mitochondrial clearance and membrane remodeling are critical in neurodegenerative disease progression including Alzheimer, but remain unclear. To investigate the potential link between full-length Myosin VI (FL-Myo6) recruitment and exposure of the mitochondria-specific lipid cardiolipin (CL), here we adapted a combination of molecular biology, biochemical, high-resolution fluorescence and interferometric light-scattering techniques. We developed analysis tools to reveal the structural Myo6-CL interaction sites, Myo6-oligomerization interfaces and mechanical properties. We found that CL activates backfolded FL-Myo6 and induces Myo6-oligomerization. Myo6 bound to CL cargo-vesicles in vitro mediates processive runs over >500 nm at >90 nm s^-1. We propose a model how CL-interaction regulates backfolded Myo6 activation into a highly processive cargo-bound motor.