Cholesterol in the cargo membrane reduces kinesin-1 binding to microtubules in the presence of tau

Intracellular cargos are often membrane-bound and transported by microtubule-based motors in the presence of microtubule-associated proteins (MAPs). Whereas increasing evidence reveals how MAPs impact the interactions between motors and microtubules, critical questions remain about the impact of the cargo membrane on transport. Here we combined in vitro optical trapping with theoretical approaches to determine the effect of a lipid cargo membrane on kinesin-based transport in the presence of MAP tau. Attaching kinesins to a fluid lipid membrane decreases the inhibitory effect of tau in comparison to membrane-free cargos. Adding cholesterol, which reduces kinesin diffusion in the cargo membrane, amplifies the inhibitory effect of tau on kinesin in a dosage-dependent manner. Our findings can be understood in a framework in which kinesin diffusion in the cargo membrane counteracts binding-site occlusion by tau. Our study establishes a direct link between the physical properties of cargo membrane and MAP-based regulation of kinesin-1.