Helical microtubule arrays in a collection of twisting tubulin mutants of Arabidopsis thaliana
Helical microtubule arrays in a collection of twisting tubulin mutants of Arabidopsis thaliana
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DOI：
10.1073/pnas.0701224104
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发表时间：
2007-05-15
影响因子：
11.1
通讯作者：
Hashimoto, Takashi
中科院分区：
文献类型：
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作者：
Ishida, Takashi;Kaneko, Yayoi;Hashimoto, Takashi
植物细胞的各向异性扩张需要皮层微管的有序排列。据报道，微管相关蛋白的突变和α-微管蛋白的特定突变会导致拟南芥中微管阵列异常并导致螺旋状生长。然而，这些突变影响微管组织的方式仍然未知。我们在这里确定了32个拟南芥扭曲突变体，有错义或氨基酸缺失突变的α或β微管蛋白。将突变定位于α-微管蛋白中的GTIPase激活区、微管蛋白异二聚体的二聚体内和二聚体间界面以及相邻原丝之间的侧向接触区。这些显性负微管蛋白突变体被纳入微管聚合物和形成浅螺旋阵列的独特的手性沿着长轴的根表皮细胞。一个惊人的相关性之间存在的方向，其中皮层螺旋阵列是偏斜和伸长的根的生长方向。GTP酶激活区突变体具有由高度稳定的微管组成的左手螺旋阵列，其可以用另外的尖端定位的End Binding 1蛋白沿着沿着整个微管晶格进行装饰。另一方面，在二聚体内界面的突变产生了高度动态的微管和右手螺旋阵列。野生型和这两种微管蛋白突变体的皮层微管主要由13条原丝组成。微管蛋白突变的全面分析提供了深入了解微管蛋白结构影响微管动力学和组织的机制。
Anisotropic expansion of plant cells requires organized arrays of cortical microtubules. Mutations in microtubule-associated proteins and a particular mutation in alpha-tubulins were reported to cause abnormal microtubule arrays and result in helical growth in Arabidopsis thahana. However, the way in which these mutations affect the organization of microtubules remains unknown. We here identified 32 Arabidopsis twisting mutants that have either missense or amino acid deletion mutations in alpha- or beta-tubulins. Mutations were mapped to the GTIPase-activating region in a-tubulin, intra- and interdimer interfaces of tubulin heterodimers, and lateral contact regions among adjacent protofilaments. These dominant-negative tubulin mutants were incorporated into the microtubuile polymer and formed shallow helical arrays of distinct handedness along the long axis of the root epidermal cells. A striking correlation exists between the direction in which cortical helical arrays are skewed and the growth direction of elongating roots. The GTPase-activating-region mutant had left-handed helical arrays composed of highly stabilized microtubules, which could be decorated along the entire microtubule lattices with the otherwise tip-localized End Binding 1 protein. A mutation at the intradimer interface, on the other hand, generated highly dynamic microtubules and right-handed helical arrays. Cortical microtubules in wild type and these two tubulin mutants were composed mainly of 13 protofilaments. This comprehensive analysis of tubulin mutations provides insights into the mechanism by which tubulin structures influence microtubulle dynamics and organization.