Motor Clustering Enhances Kinesin-driven Vesicle Transport

Intracellular vesicles are typically transported by a small number of kinesin and dynein motors. However, the slow microtubule binding rate of kinesin-1 observed in in vitro biophysical studies suggests that long-range transport may require a high number of motors. To address the discrepancy in motor requirements between in vivo and in vitro studies, we reconstituted motility of 120-nm-diameter liposomes driven by multiple GFP-labeled kinesin-1 motors. Consistent with predictions based on previous binding rate measurements, we found that long-distance transport requires a high number of kinesin-1 motors. We hypothesized that this discrepancy from in vivo observations may arise from differences in motor organization and tested whether motor clustering can enhance transport efficiency using a DNA scaffold. Clustering just three motors improved liposome travel distances across a wide range of motor numbers. Our findings demonstrate that, independent of motor number, the arrangement of motors on a vesicle regulates transport distance, suggesting that differences in motor organization may explain the disparity between in vivo and in vitro motor requirements for long-range transport. Significance StatementIntracellular vesicles frequently travel long distances, despite having few kinesin and dynein motors. By reconstituting liposome motility with kinesin-1 motors, we demonstrate the need for high motor copy numbers for long-range transport when motors are randomly distributed on the liposome surface. We further show that motor clustering reduces the required motor number, emphasizing its potential role in enhancing transport efficiency. Our findings highlight the significance of motor organization in regulating intracellular transport and suggest that motor clustering, such as by scaffolding proteins or lipid domains, influences bidirectional transport outcomes.