Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 33: Cytoskeletal Filaments II

BP 33.5: Vortrag

Donnerstag, 15. März 2018, 16:15–16:30, H 1028

Rotational movement of microtubules driven by thermal forces and by kinesin-5 motors leads to mitotic spindle formation — •Ivana Ban¹, Marcel Prelogović¹, Lora Winters², Iva Tolić^2,3, and Nenad Pavin¹ — ¹Faculty of science, University of Zagreb, Croatia — ²Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany — ³Division of Molecular Biology, Ruder Bošković Institute, Zagreb, Croatia

During mitosis, the spindle divides chromosomes between two daughter cells. In the fission yeast Schizosaccharomyces pombe, the rod shaped mitotic spindle is composed of antiparallel microtubules (MTs) emanating from two opposite spindle poles, whose formation is mediated by motor proteins. A key question is what are the physical principles underlying the formation of a mitotic spindle. Here we show, experimentally and theoretically, that MTs at one pole search for a MT from the other pole by performing random rotational movement around the spindle pole. When MTs from opposite poles get into close proximity, motor proteins start to accumulate in the region where MTs are close to each other. In our model, minus end directed motors generate forces that drive the formation of an antiparallel MT bundle, thereby forming the mitotic spindle. We identified experimentally the kinesin-5 motor Cut7 as the main force generator in this process. In conclusion, random rotational motion helps MTs from opposite poles to find each other and subsequent accumulation of kinesin-5 motors allows them to generate forces that drive spindle formation.