Altered microtubule dynamics by expression of modified α-tubulin protein causes right-handed helical growth in transgenic Arabidopsis plants
Altered microtubule dynamics by expression of modified α-tubulin protein causes right-handed helical growth in transgenic Arabidopsis plants
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DOI：
10.1111/j.1365-313x.2005.02442.x
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发表时间：
2005-07-01
期刊：
影响因子：
7.2
通讯作者：
Hashimoto, T
中科院分区：
文献类型：
--
作者：
Abe, T;Hashimoto, T
皮质微管阵列的正确组织对于植物的各向异性生长至关重要，但不同的阵列模式是如何形成的尚不清楚。在这里，我们使用表达修饰的微管蛋白的转基因植物报告了微管动力学和阵列组织之间的关系。当绿色荧光蛋白 (GFP) 或血凝素表位标签融合到微管蛋白的 N 末端并在拟南芥植物中表达时，这些微管蛋白与内源微管蛋白一起掺入微管中。表达修饰的β-微管蛋白的植物表型正常，并且在根伸长区的表皮细胞中具有横向定向的皮质阵列；然而，修饰的α-微管蛋白的表达导致右旋螺旋生长、毛状体分支增加和浅左旋（S型）螺旋阵列组织。与对照细胞相比，在表达修饰的 α-微管蛋白的细胞中，微管动态被抑制，聚合被促进，并且 GFP-EB1（末端结合 1）更频繁地标记微管末端的较大区域。我们提出，引入 α-微管蛋白的 N 末端附属物会抑制 GTP 水解，从而产生具有延长的 GTP 帽的易于聚合的微管。与这种解释一致，表达 GTP 酶激活结构域突变的 α-微管蛋白的植物在 GFP-EB1 的动力学和定位方面表现出相似的微管特性，并显示出右旋螺旋生长。
The proper organization of cortical microtubule arrays is essential for anisotropic growth in plants but how distinct array patterns are formed is not understood. Here, we report a relationship between microtubule dynamics and array organization using transgenic plants expressing modified tubulins. When green fluorescent protein (GFP) or a hemaglutinin epitope tag was fused to the N-terminus of tubulins and expressed in Arabidopsis plants, these tubulins were incorporated into microtubules along with endogenous tubulins. Plants expressing the modified beta-tubulins were phenotypically normal and possessed transversely oriented cortical arrays in the epidermal cells of the root elongation zone; however, the expression of modified alpha-tubulins caused right-handed helical growth, increased trichome branching, and a shallow left-handed (S-form) helical array organization. In cells expressing the modified alpha-tubulins, microtubule dynamicity was suppressed and polymerization was promoted, and GFP-EB1 (End Binding 1) labeled larger regions of the microtubule end more frequently, when compared with control cells. We propose that the N-terminal appendage introduced into alpha-tubulin inhibits GTP hydrolysis, thus producing polymerization-prone microtubules with an extended GTP cap. Consistent with this interpretation, plants expressing an alpha-tubulin mutated in the GTPase-activating domain exhibited similar microtubule properties, with regard to dynamics and the localization of GFP-EB1, and showed right-handed helical growth.