Motors on the move : Dissecting the interplay between kinesins and their tracks

Abstract

Cells are shaped by the cytoskeleton, a network of dynamic biopolymers and associated proteins. Among the cytoskeleton family, microtubules (MTs) are essential for processes such as cell division and intracellular transport. These processes require the coordination of the MT network and its interaction partners, MT associated proteins and motor proteins. The former regulate MT dynamics and the latter are known to transport cargoes along MT. In this thesis, I use well-controlled in vitro reconstitutions to explore the interplay between microtubules and different microtubule associated proteins (MAPs) and motors. I first examine how the interplay between microtubules and MAPs can organize membranes and demonstrate three distinct mechanisms by which membranes can be remodeled by MTs in a motor-independent fashion. The remainder of the thesis concentrates on the interaction of MTs and motor proteins. First, I use purified optogenetic modules and demonstrate that these can be used to manipulate motor-dependent forces with high spatiotemporal precision. Furthermore, I explore the mechanism by which free tubulin can enhance the motility of kinesin-1. Finally, I explore the motility of different kinesin family members on different MT subtypes. The studies presented in the thesis provide fundamental understandings of force generation in MT-membrane contacts and provide new insight into the regulation of motor proteins. These insights may support future research to better understand and control cellular processes.