Why kinesin is so processive Export

@article{citeulike:5172589, abstract = {10.1073/pnas.0808396106 Kinesin I can walk on a microtubule for distances as long as several micrometers. However, it is still unclear how this molecular motor can remain attached to the microtubule through the hundreds of mechanochemical cycles necessary to achieve this remarkable degree of processivity. We have addressed this issue by applying ensemble and single-molecule fluorescence methods to study the process of kinesin stepping, and our results lead to 4 conclusions. First, under physiologic conditions, ≈75\% of processively moving kinesin molecules are attached to the microtubule via both heads, and in this conformation, they are resistant to dissociation. Second, the remaining 25\% of kinesin molecules, which are in an ” ATP waiting state” and are strongly attached to the microtubule via only one head, are intermittently in a conformation that cannot bind ATP and therefore are resistant to nucleotide-induced dissociation. Third, the forward step in the kinesin ATPase cycle is very fast, accounting for <5\% of the total cycle time, which ensures that the lifetime of this ATP waiting state is relatively short. Finally, by combining nanometer-level single-molecule fluorescence localization with higher ATP concentrations than used previously, we have determined that in this ATP waiting state, the ADP-containing head of kinesin is located 8 nm behind the attached head, in a location where it can interact with the microtubule lattice. These 4 features reduce the likelihood that a kinesin I motor will dissociate and contribute to making this motor so highly processive.}, author = {Toprak, Erdal and Yildiz, Ahmet and Hoffman, Melinda T. and Rosenfeld, Steven S. and Selvin, Paul R.}, citeulike-article-id = {5172589}, citeulike-linkout-0 = {http://dx.doi.org/10.1073/pnas.0808396106}, citeulike-linkout-1 = {http://www.pnas.org/content/early/2009/07/14/0808396106.abstract}, citeulike-linkout-2 = {http://www.pnas.org/content/early/2009/07/14/0808396106.full.pdf}, day = {15}, doi = {10.1073/pnas.0808396106}, journal = {Proceedings of the National Academy of Sciences}, keywords = {fluorescence, kinesin, motor-protein, single-molecule}, month = {July}, posted-at = {2009-07-16 03:24:52}, priority = {0}, title = {Why kinesin is so processive}, url = {http://dx.doi.org/10.1073/pnas.0808396106}, year = {2009} }

TY - JOUR ID - citeulike:5172589 L3 - citeulike-article-id:5172589 N2 - 10.1073/pnas.0808396106 Kinesin I can walk on a microtubule for distances as long as several micrometers. However, it is still unclear how this molecular motor can remain attached to the microtubule through the hundreds of mechanochemical cycles necessary to achieve this remarkable degree of processivity. We have addressed this issue by applying ensemble and single-molecule fluorescence methods to study the process of kinesin stepping, and our results lead to 4 conclusions. First, under physiologic conditions, ≈75% of processively moving kinesin molecules are attached to the microtubule via both heads, and in this conformation, they are resistant to dissociation. Second, the remaining 25% of kinesin molecules, which are in an “ATP waiting state” and are strongly attached to the microtubule via only one head, are intermittently in a conformation that cannot bind ATP and therefore are resistant to nucleotide-induced dissociation. Third, the forward step in the kinesin ATPase cycle is very fast, accounting for <5% of the total cycle time, which ensures that the lifetime of this ATP waiting state is relatively short. Finally, by combining nanometer-level single-molecule fluorescence localization with higher ATP concentrations than used previously, we have determined that in this ATP waiting state, the ADP-containing head of kinesin is located 8 nm behind the attached head, in a location where it can interact with the microtubule lattice. These 4 features reduce the likelihood that a kinesin I motor will dissociate and contribute to making this motor so highly processive. JF - Proceedings of the National Academy of Sciences TI - Why kinesin is so processive KW - fluorescence KW - kinesin KW - motor-protein KW - single-molecule AU - Toprak, Erdal AU - Yildiz, Ahmet AU - Hoffman, Melinda AU - Rosenfeld, Steven AU - Selvin, Paul PY - 2009/07/15/ UR - http://dx.doi.org/10.1073/pnas.0808396106 ER -