Role of confinement in the active self-organization of kinesin-driven microtubules

Self-organization is one of the most spectacular phenomena exhibited in the wide spectrum of biologically active systems. Many studies have attempted to investigate different parameters that regulate the self-organization of moving objects. Recent theoretical and analytical-based approaches have revealed that physical confinement has regulatory effect on the self-organization of moving objects. However, a detailed experimental study on how the varying shapes and sizes of the confinement affect the self-organization of moving objects is still lacking. Recently, biomolecular motor systems F-actin/myosin and microtubule/kinesin or microtubule/dynein have been promising to experimentally study the self-organization of moving objects. Here, we experimentally investigated the shape and size effect of confinement on the self-organization of microtubules (MTs) by employing the in vitro motility assay of MT/kinesin motor system. The MTs were confined by a lipid layer on a glass surface micro-patterned by photolithography. We demonstrated that shapes and sizes of the confinements largely influenced the self-organization of MTs. The MTs showed distinct orientations in different shapes and sizes of the confinements. This work clearly unveiled how physical confinement influences the self-organization of MTs and would help understand the effect of confinement on the self-organization of more complex biologically active systems in nature.