Venier P, Maggs A C, Carlier M F, Pantaloni D
Laboratoire d'Enzymologie, CNRS, 91198 Gif-sur-Yvette, France.
J Biol Chem. 1994 May 6;269(18):13353-60.
We report the use of two independent new methods to measure the flexural rigidity of microtubules. Microtubules were grown off axonemal pieces adhering to a glass coverslip. In the first method, a hydrodynamic flow was applied to microtubules and the flexural rigidity was derived from the analysis of the bending shape of the microtubules at equilibrium in the flow. In the second method, the flexural rigidity was derived from the thermal fluctuations of the free end of axoneme-bound microtubules. With both methods, the flexural rigidity of standard GDP microtubules was estimated to be 0.85 +/- 0.2 x 10(-23) newtons x m2 which corresponded to a persistence length of 2 +/- 0.2 mm. Binding of ligands known to affect the biochemical properties of microtubules affected their rigidity. The structural analogs of inorganic phosphate AlF4- and [BeF3-, H2O], which bind to the site of the gamma-phosphate of GTP on GDP microtubule and reconstitute the GDP-Pi microtubule intermediate state of GTP hydrolysis, cause an approximately 3-fold increase in microtubule flexural rigidity and persistence length. Taxol and taxotere, antitumoral microtubule-stabilizing drugs, in contrast cause a decrease in flexural rigidity and appear to affect the three-dimensional superstructure of microtubules, which can no longer be considered as semi-flexible rods. The relationship between the mechanical properties of microtubules and their biological function is discussed.
我们报告了使用两种独立的新方法来测量微管的抗弯刚度。微管从附着在玻璃盖玻片上的轴丝片段上生长出来。在第一种方法中，对微管施加流体动力流，并通过分析微管在流中达到平衡时的弯曲形状来推导抗弯刚度。在第二种方法中，抗弯刚度是从轴丝结合的微管自由端的热涨落推导出来的。使用这两种方法，标准GDP微管的抗弯刚度估计为0.85±0.2×10⁻²³牛顿·平方米，这对应于2±0.2毫米的持续长度。已知影响微管生化特性的配体结合会影响其刚度。无机磷酸盐AlF₄⁻和[BeF₃⁻, H₂O]的结构类似物，它们与GDP微管上GTP的γ-磷酸位点结合并重建GTP水解的GDP- Pi微管中间状态，导致微管抗弯刚度和持续长度增加约3倍。相比之下，紫杉醇和多西他赛这两种抗肿瘤微管稳定药物会导致抗弯刚度降低，并且似乎会影响微管的三维超结构，微管不再能被视为半柔性杆。本文讨论了微管的力学性质与其生物学功能之间的关系。
