Le Jie, El-Assal Salah El-Din, Basu Dipanwita, Saad Mohamed E, Szymanski Daniel B
Agronomy Department, Purdue University, Lily Hall, 915 West State Street, West Lafayette, IN 47907-2054, USA.
Curr Biol. 2003 Aug 5;13(15):1341-7. doi: 10.1016/s0960-9822(03)00493-7.
Plant cells employ the actin cytoskeleton to stably position organelles, as tracks for long distance transport, and to reorganize the cytoplasm in response to developmental and environmental cues. While diverse classes of actin binding proteins have been implicated in growth control, the mechanisms of cytoskeletal reorganization and the cellular functions of specific actin filament arrays are unclear. Arabidopsis trichome morphogenesis includes distinct requirements for the microtubule and actin filament cytoskeletons. It also is a genetically tractable process that is providing new knowledge about cytoskeleton function in plants. The "distorted group" of mutants defines a class of at least eight genes that are required during the actin-dependent phase of trichome growth. Using map-based cloning and a candidate gene approach, we identified mutations in ARP3 (ATARP3) and ARP2 (ATARP2) genes as the cause of the distorted1 (dis1) and wurm (wrm) phenotypes, respectively. ARP2 and ARP3 are components of the evolutionarily conserved ARP2/3 complex that nucleates actin filament polymerization [3]. Mutations in DIS1 and WRM caused severe trichome growth defects but had relatively mild effects on shoot development. DIS1 rescued the phenotype of Deltaarp3 when overexpressed in S. cerevisiae. Developing dis1 trichomes had defects in cytoplasmic actin bundle organization and reduced relative amounts of cytoplasmic actin filaments in developing branches.
植物细胞利用肌动蛋白细胞骨架来稳定细胞器的位置,作为长距离运输的轨道,并响应发育和环境线索来重组细胞质。虽然不同种类的肌动蛋白结合蛋白与生长控制有关,但细胞骨架重组的机制以及特定肌动蛋白丝阵列的细胞功能尚不清楚。拟南芥毛状体形态发生对微管和肌动蛋白丝细胞骨架有不同的要求。它也是一个遗传上易于处理的过程,正在提供有关植物细胞骨架功能的新知识。“畸变组”突变体定义了一类至少八个基因,这些基因在毛状体生长的肌动蛋白依赖性阶段是必需的。使用基于图谱的克隆和候选基因方法,我们分别鉴定出ARP3(ATARP3)和ARP2(ATARP2)基因中的突变是畸变1(dis1)和蠕虫(wrm)表型的原因。ARP2和ARP3是进化上保守的ARP2/3复合物的组成部分,该复合物引发肌动蛋白丝聚合[3]。DIS1和WRM中的突变导致严重的毛状体生长缺陷,但对茎发育的影响相对较小。当在酿酒酵母中过表达时,DIS1挽救了Deltaarp3的表型。发育中的dis1毛状体在细胞质肌动蛋白束组织方面存在缺陷,并且发育中的分支中细胞质肌动蛋白丝的相对量减少。