Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Structure. 2010 Aug 11;18(8):1022-31. doi: 10.1016/j.str.2010.05.010.
The diverse functions of microtubules require stiff structures possessing sufficient lateral flexibility to enable bending with high curvature. We used cryo-electron microscopy to investigate the molecular basis for these critical mechanical properties. High-quality structural maps were used to build pseudoatomic models of microtubules containing 11-16 protofilaments, representing a wide range of lateral curvature. Protofilaments in all these microtubules were connected primarily via interprotofilament interactions between the M loops, and the H1'-S2 and H2-S3 loops. We postulate that the tolerance of the loop-loop interactions to lateral deformation provides the capacity for high-curvature bending without breaking. On the other hand, the local molecular architecture that surrounds these connecting loops contributes to the overall rigidity. Interprotofilament interactions in the seam region are similar to those in the normal helical regions, suggesting that the existence of the seam does not significantly affect the mechanical properties of microtubules.
微管的多种功能需要刚性结构，同时具有足够的横向灵活性，以实现高曲率弯曲。我们使用冷冻电子显微镜研究了这些关键力学性能的分子基础。高质量的结构图谱被用于构建包含 11-16 个原丝的微管的拟原子模型，这些模型代表了广泛的横向曲率范围。所有这些微管中的原丝主要通过 M 环之间、H1'-S2 和 H2-S3 环之间的原丝间相互作用连接。我们推测，环-环相互作用对横向变形的容忍度为高曲率弯曲提供了能力，而不会断裂。另一方面，环绕这些连接环的局部分子结构有助于整体刚性。缝区的原丝间相互作用与正常螺旋区的相互作用相似，这表明缝的存在不会显著影响微管的力学性能。
