@article {Grover064246, author = {Rahul Grover and Janine Fischer and Friedrich W. Schwarz and Wilhelm J. Walter and Petra Schwille and Stefan Diez}, title = {Transport efficiency of membrane-anchored kinesin-1 motors depends on motor density and diffusivity}, elocation-id = {064246}, year = {2016}, doi = {10.1101/064246}, publisher = {Cold Spring Harbor Laboratory}, abstract = {In eukaryotic cells, membranous vesicles and organelles are transported by ensembles of motor proteins. These motors, such as kinesin-1, have been well characterized in vitro as single molecules or as ensembles rigidly attached to non-biological substrates. However, the collective transport by membrane-anchored motors, i.e. motors attached to a fluid lipid bilayer, is poorly understood. Here, we investigate the influence of motors anchorage to a lipid bilayer on the collective transport characteristics. We reconstituted {\textquoteleft}membrane-anchored{\textquoteright} gliding motility assays using truncated kinesin-1 motors with a streptavidin-binding-peptide tag that can attach to streptavidin-loaded, supported lipid bilayers. We found that the diffusing kinesin-1 motors propelled the microtubules in presence of ATP. Notably, we found the gliding velocity of the microtubules to be strongly dependent on the number of motors and their diffusivity in the lipid bilayer. The microtubule gliding velocity increased with increasing motor density and membrane viscosity, reaching up to the stepping velocity of single-motors. This finding is in contrast to conventional gliding motility assays where the density of surface-immobilized kinesin-1 motors does not influence the microtubule velocity over a wide range. We reason, that the transport efficiency of membrane-anchored motors is reduced because of their slippage in the lipid bilayer, an effect which we directly observed using singlemolecule fluorescence microscopy. Our results illustrate the importance of the motor-cargo coupling, which potentially provides cells with an additional means of regulating the efficiency of cargo transport.}, URL = {https://www.biorxiv.org/content/early/2016/07/15/064246}, eprint = {https://www.biorxiv.org/content/early/2016/07/15/064246.full.pdf}, journal = {bioRxiv} }