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Before cell division, two identical copies of chromosome need to be segregated accurately. Each chromosome is connected to a "nano-ring" (dam1) by "rods" (Ndc80). For accurate chromosome segregation, the two chromosomes are pulled apart in the opposite directions by two sets of "nano-hooks", formed by microtubules (MTs), that are inserted into these rings. An externally applied tension can lead to detachment of the hooks from the ring; the mean lifetime of such an attachment is essentially a mean first-passage time. Recent pioneering in-vitro experiments with reconstituted nano hook-ring device established that the mean lifetimes of such attachments vary non-monotonically with increasing tension. In this talk I'll explain the counter-intuitive stabilization of the attachments by small tension with a unified model that we have developed very recently. The catch-bond-like mechanism emerges naturally in this model from the interplay of tension-dependence of (i) the potential landscape and (ii) MT depolymerization rate. I'll also show how the distribution of lifetimes of the hook-ring attachment depends on (a) the structure, (b) energetics, and (c) kinetics of the coupling.

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Prof. Debashish Chowdhury, Indian Institute of Technology, Kanpur
Seminarraum Theoretische Physik
Contact: not specified