Changes of affinity of kinesin head to microtubule regulated by changes in the nucleotide state are essential to processive movement of kinesin on microtubule. Here, using all-atom molecular dynamics simulations we show that besides the nucleotide state, large conformational changes of microtubule-tubulin heterodimers induced by strong interaction with the head in strongly binding state are also indispensable to regulate the affinity of the head to the tubulin. In strongly binding state the high affinity of the head to microtubule arises largely from mutual conformational changes of the microtubule and head induced by the specific interaction between them via an induced-fit mechanism. Moreover, the ADP-head has a much weaker affinity to the local microtubule-tubulin, whose conformation is largely altered by the interaction with the head in strongly binding state, than to other unperturbed tubulins. This indicates that upon Pi release the ADP-head temporarily has a much weaker affinity to the local tubulin than to other tubulins.
Keywords: binding affinity; conformational changes; induced-fit mechanism; kinesin; microtubule; molecular dynamics simulation.
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