Motility of plant myosins - structure-function relationships

虽然典型的植物细胞由于坚硬的细胞壁而不能移动，但它拥有高度活跃的细胞内移动。这种移动性是必不可少的，因为植物细胞非常大，必须适应几乎没有缓冲的环境。当前植物生物学中的一个主题是通过信号成分的定向运输来依赖于信号来建立细胞极性。在此背景下，植物肌球蛋白起着关键作用。尽管它们与动物具有相同的基本领域，但人们发现它们的差异如此之大，以至于它们不得不被分配到不同的班级。到目前为止，已知的最快的细胞内运动是由植物肌球蛋白产生的。然而，到目前为止，这种高运动性的结构基础和生物学功能都还不清楚。利用高等植物肌球蛋白类(类和XI类)的成员，我们希望通过体外运动试验来研究这些马达蛋白的生化性质，重点是运动的速度和过程，三磷酸腺苷结合的时间过程以及与F-肌动蛋白的联系。体内的功能将通过瞬时导入完整的同源系统的荧光融合构建体来研究。利用这些肌球蛋白的零突变植物，我们希望将特定的功能分配给各个肌球蛋白类别。这将有助于提出这样一个问题：植物-肌球蛋白运动域的特定功能是否与特定的细胞和/或发育功能相关。

Although the typical plant cell is immobile due to rigid cell walls, it harbours a highly active intracellular mobility. This mobility is essential because plant cells are very large and have to adjust to a mostly unbuffered environment. A current topic in plant biology is the signal-dependent establishment of cell polarity by directional transport of signalling components. In this context, plant myosins play a pivotal role. Although they share the basic domains with their animal counterparts, they have been found to differ to such a degree that they had to be assigned to separate classes. The fastest intracellular movements known so far are produced by plant myosins. However, neither the structural base for this high motility nor its biological function have been understood so far. Using members from the myosin classes of higher plants (class VIII and XI), we want to investigate the biochemical properties of these motor proteins by in vitro motility assays focussing on velocity and processivity of the movement, time course of ATP-binding and the association with F-actin. Functionality in vivo will be studied by fluorescent fusion constructs transiently transfected into the intact, homologous system. Using plants that are null-mutants for these myosins, we want to assign specific functions to the individual myosin classes. This will contribute to the question whether specific features of the plant-myosin motor domain can be correlated to specific cellular and/or developmental functions.