A Fluid Membrane Enhances The Velocity of Cargo Transport by Small Teams of Kinesin-1

Kinesin-1 is a major molecular motor driving the fundamental process of transport in live cells. While the single-molecule functions of kinesin are well characterized, the physiologically relevant transport of membranous cargos by small teams of kinesins remains poorly understood. A key experimental challenge remains in the quantitative control of the number of motors driving transport. Here we utilized “motile fraction” to overcome this challenge, and experimentally accessed transport by a single kinesin through the physiologically relevant transport by a small team of kinesins. We used a fluid lipid bilayer to model the cellular membrane in vitro, and employed optical trapping to quantify transport of membrane-enclosed cargos versus traditional membrane-free cargos under otherwise identical conditions. We found that coupling motors via a fluid membrane significantly enhances the velocity of cargo transport by small teams of kinesins; this velocity enhancement arises from altered interactions between kinesins. Our study demonstrates that membrane-based coupling between motors is a key determinant of kinesin-based transport. Enhanced velocity may be critical for the timely delivery of cargos in live cells.