Investigating Structure, Function, and Evolution of a Plant-Specific Nuclear Envelope Targeting Domain.

该项目的长期目标是了解核膜靶向机制的分子机制、生物学功能和进化历史，这种机制可能是植物界独有的。RanGAP是RAN信号的辅助蛋白，在核转运、有丝分裂纺锤体组装和有丝分裂后核组装中发挥作用。在高等植物和哺乳动物中，RanGAP在间期定位于核膜，在中期定位于纺锤体，而在酵母中不定位。植物RanGAP特有的结构域(WPP结构域)负责其靶向植物核膜。该项目的首要假设是，RanGAP的两种不同的靶向机制已经在动植物中进化，这可能反映--并因此提供工具--植物和动物开放有丝分裂的分子机制的更广泛的差异。本项目将进行的实验将：(1)测试植物RanGAP的功能是否需要核包膜靶向。(2)确定拟南芥MAF蛋白家族(一个类似于独立的WPP结构域的小的植物特有蛋白家族)的成员是否参与将RanGAP靶向植物核膜。(3)为确定WPP域的结构创造条件。这种新的、植物特有的结构域的高分辨率结构将为预测驱动的未来结构-功能关系和进化多样性的研究提供强大的信息。(4)鉴定具有封闭有丝分裂的绿藻莱茵衣藻RanGAP的结构和定位。该项目的更广泛影响将包括教授和培训下一代博士后、研究生和本科生水平的科学家。该项目将进一步促进多学科活动，并为已经建立的植物分子生物学、细胞生物学、蛋白质组学和计算生物学领域增加进化和生物物理方面的内容。将通过出版物、审查、研讨会、科学会议和创新课堂教学来传播成果。将为广大公众开发一种学习工具。

The long-term goal of this project is to understand the molecular mechanism, biological function, and evolutionary history of a nuclear-envelope targeting mechanism that may be unique to the plant kingdom. RanGAP is an accessory protein of Ran signaling, which functions in nuclear transport, mitotic spindle assembly, and post-mitotic nuclear assembly. RanGAP is targeted to the nuclear envelope in interphase and to the spindle in metaphase in higher plants and mammals, but not in yeast. A domain unique to plant RanGAP (WPP domain) is responsible for its targeting to the plant nuclear envelope. The overarching hypothesis of this project is that two distinct targeting mechanisms for RanGAP have evolved in the plant and animal kingdom, which might reflect - and therefore provide tools to investigate - broader differences in the molecular mechanisms of plant and animal open mitosis. Experiments to be carried out in this project will: (1) Test if nuclear envelope targeting is required for the function of plant RanGAP. (2) Identify if members of the Arabidopsis MAF protein family (a family of small, plant-specific proteins that resemble an unattached WPP domain) are involved in targeting RanGAP to the plant nuclear envelope. (3) Establish conditions for determining the structure of the WPP domain. A high-resolution structure of this novel, plant-specific domain would provide powerful information for prediction-driven future investigations into structure-function relationships and evolutionary diversity. (4) Identify domain structure and localization of RanGAP in Chlamydomonas reinhardtii, a green alga with closed mitosis. The broader impacts of this project will include teaching and training of the next generation of scientists at the postdoctoral, graduate student, and undergraduate level. This project will further contribute to multidisciplinary activities and add an evolutionary and a biophysical aspect to already established areas of plant molecular biology, cell biology, proteomics, and computational biology. Dissemination of results will be through publications, reviews, seminars, scientific meetings, and through innovative classroom teaching. A learning tool for the broad public will be developed.