Ligand Binding Swaps between Soft Internal Modes of α,β-Tubulin and Alters Its Accessible Conformational Space

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• 作者：Sarmistha Majumdar ; Shubhra Ghosh Dastidar
• 刊名：Journal of Physical Chemistry B
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：118-128
• 全文大小：672K
• ISSN：1520-5207

文摘

The dynamic instability of the microtubule originates from the conformational switching of its building block, that is, the α, β-tubulin dimer. Ligands occupying the interface of the α–β dimer bias the switch toward the disintegration of the microtubule, which in turn controls the cell division. A little loop of tubulin is structurally encoded as a biophysical “gear” that works by changing its structural packing. The consequence of such change propagates to the quaternary level to alter the global dynamics and is reflected as a swapping between the relative contributions of dominating internal modes. Simulation shows that there is an appreciable separation between the conformational space accessed by the liganded and unliganded systems; the clusters of conformations differ in their intrinsic tendencies to “bend” and “twist”. The correlation between the altered breathing modes and conformational space rationally hypothesizes a mechanism of straight−bent interconversion of the system. In this mechanism, a ligand is understood to bias the state of the “gear” that detours the conformational equilibrium away from its native preference. Thus, a fundamental biophysical insight into the mechanism of the conformational switching of tubulin is presented as a multiscale process that also shows promise to yield newer concept of ligand design.