Geometry of antiparallel microtubule bundles regulates relative sliding and stalling by PRC1 and Kif4A

Motor and non-motor crosslinking proteins play critical roles in determining the size and stability of microtubule-based architectures. Currently, we have a limited understanding of how the geometrical properties of microtubule arrays, in turn, regulate the output of the crosslinking proteins. Here we investigate this problem in the context of microtubule organization by two interacting proteins: the non-motor crosslinker PRC1 and the kinesin Kif4A. We show that the collective activity of both proteins results in both the relative sliding of antiparallel microtubules and the accumulation of PRC1 and Kif4A molecules at the plus-end of each microtubule (‘end-tag’). Sliding stalls when the end-tags on the two microtubules collide, resulting in the organization of a stable antiparallel overlap. Interestingly, we find that structural properties of the initial array regulate two aspects of PRC1-Kif4A mediated microtubule organization. First, sliding velocity scales with initial microtubule-overlap length. Second, the width of the final stable overlap scales with microtubule lengths. Our analyses provide insights into how the micron-scale geometrical features of antiparallel microtubule bundles can be decoded by nanometer-sized proteins to define the structure and mechanics of microtubule-based architectures.