Wood Cell-Wall Structure Requires Local 2D-Microtubule Disassembly by a Novel Plasma Membrane-Anchored Protein
Wood Cell-Wall Structure Requires Local 2D-Microtubule Disassembly by a Novel Plasma Membrane-Anchored Protein
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DOI：
10.1016/j.cub.2010.05.038
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发表时间：
2010-07-13
期刊：
影响因子：
9.2
通讯作者：
Fukuda, Hiroo
中科院分区：
文献类型：
--
作者：
Oda, Yoshihisa;Iida, Yuki;Fukuda, Hiroo
植物细胞已经在质膜[1，2]下方的二维空间中进化出皮质微管，它调节纤维素沉积的图案[3]。虽然最近的研究表明，几种微管相关蛋白[4-8]促进了横向皮质微管的自组织[9-11]，但仍不清楚不同的皮质微管是如何在不同的木质部细胞中组织起来的[12-17]，木质部细胞是木材的主要成分。利用我们新建立的木质部细胞体外分化系统，我们发现一种新的微管末端跟踪蛋白微管耗竭结构域1(MIDD1)被锚定在不同的质膜结构域上，并促进局部微管的解体，导致木质部细胞壁上出现凹坑。对MIDD1基因的RNA干扰导致了微管局部耗竭的失败和次生壁的形成。反之，MIDD1的过表达降低了微管密度。MIDD1有两个卷曲的结构域，分别用于结合微管和锚定质膜结构域。这两个线圈的结合导致微管在收缩过程中的末端跟踪，并抑制了它们的救援事件。我们的结果表明，MIDD1结合了质膜上的空间信息和皮质微管的动力学来确定木质部细胞壁的模式。
Plant cells have evolved cortical microtubules, in a two-dimensional space beneath the plasma membrane [1, 2], that regulate patterning of cellulose deposition [3]. Although recent studies have revealed that several microtubule-associated proteins [4-8] facilitate self-organization of transverse cortical microtubules [9-11], it is still unknown how diverse patterns of cortical microtubules are organized in different xylem cells [12-17], which are the major components of wood. Using our newly established in vitro xylem cell differentiation system, we found that a novel microtubule end-tracking protein, microtubule depletion domain 1 (MIDD1), was anchored to distinct plasma membrane domains and promoted local microtubule disassembly, resulting in pits on xylem cell walls. The introduction of RNA interference for MIDD1 resulted in the failure of local microtubule depletion and the formation of secondary walls without pits. Conversely, the overexpression of MIDD1 reduced microtubule density. MIDD1 has two coiled-coil domains for the binding to microtubules and for the anchorage to plasma membrane domains, respectively. Combination of the two coils caused end tracking of microtubules during shrinkage and suppressed their rescue events. Our results indicate that MIDD1 integrates spatial information in the plasma membrane with cortical microtubule dynamics for determining xylem cell wall pattern.