Application of pulling force, under force-clamp conditions, to kinetochore-microtubule attachments {\it in-vitro}  revealed a catch-bond-like behavior. In an earlier paper (%DIFDELCMD < {\it %%% Sharma et al. Phys. Biol. (2014) the physical origin of this apparently counter-intuitive phenomenon was traced to the nature of the force-dependence of the (de-)polymerization kinetics of the microtubules. In this brief communication that work is extended to situations where the external forced is ramped up till the attachment gets ruptured . In spite of the fundamental differences in the underlying mechanisms, the trend of variation of the rupture force distribution observed in our model kinetochore-microtubule attachment with the increasing loading rate is qualitatively similar to that displayed by the catch bonds formed in some other ligand-receptor systems. Our theoretical predictions can be tested experimentally by a straightforward modification of the protocol for controlling the force in the optical trap set up that was used in the original experiments under force-clamp conditions .
Measurement of the life time of attachments formed by a single microtubule (MT) with a single kinetochore (kt) {\it in-vitro} under force-clamp conditions revealed a catch-bond-like behavior. In %DIFDELCMD < {\it %%% the past the physical origin of this apparently counter-intuitive phenomenon was traced to the nature of the force-dependence of the (de-)polymerization kinetics of the microtubules. Here first the same model kt-MT attachment is subjected to external tension that is ramped up till the attachment gets ruptured ; the trend of variation of the rupture force distribution with increasing loading rate is consistent with that displayed by the catch bonds formed in some other ligand-receptor systems. We then extend the formalism to model an attachment of a bundle of multiple parallel microtubules with a single kt under force-clamp and force-ramp conditions. From numerical studies of the model we predict the trends of variation of the mean life time and mean rupture force with the increasing number of MTs in the bundle. Both the mean life time and the mean rupture force display nontrivial nonlinear dependence on the maximum number of MTs that can attach simultaneously to the same kt .
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Application of pulling force, under force-clamp conditions, to kinetochore-microtubule attachments
Measurement of the life time of attachments formed by a single microtubule (MT) with a single kinetochore (kt)
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an earlier paper (
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Sharma et al. Phys. Biol. (2014)
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In this brief communication that work is extended to situations where the external forced
Here first the same model kt-MT attachment is subjected to external tension that
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. In spite of the fundamental differences in the underlying mechanisms, the
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observed in our model kinetochore-microtubule attachment with the
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qualitatively similar to
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Our theoretical predictions can be tested experimentally by a straightforward modification of the protocol for controlling the force in the optical trap set up that was used in the original experiments under
We then extend the formalism to model an attachment of a bundle of multiple parallel microtubules with a single kt under
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conditions
and force-ramp conditions. From numerical studies of the model we predict the trends of variation of the mean life time and mean rupture force with the increasing number of MTs in the bundle. Both the mean life time and the mean rupture force display nontrivial nonlinear dependence on the maximum number of MTs that can attach simultaneously to the same kt