2009年8月28日, 北京生命科学研究所邓兴旺实验室在The Plant Cell杂志上在线发表题为 ”Biochemical Insights on Degradation of Arabidopsis DELLA Proteins Gained From A Cell-free Assay System”的文章。 该文章通过建立体外降解系统, 对GA调控的DELLA蛋白的降解机理进行了深入的生化分析。
DELLA蛋白作为GA信号传导途径中的主要负调控因子, 同时也是整合其他植物激素或环境信号的枢纽蛋白来调节植物的生长发育过程。植物体接受GA信号后, 通过泛素-蛋白酶体途径降解DELLA蛋白来解除其对生长的抑制作用。 该文章通过建立DELLA蛋白体外降解体系对其降解机理进行分析。 利用该体外降解系统, 作者验证了GA受体和SCF泛素连接酶复合体在DELLA蛋白降解中的重要作用。并且,发现了泛素分子的第29位赖氨酸可能是介导DELLA蛋白降解中泛素链形成的一个重要位点, 与经典的第48位赖氨酸起功能协同作用。 通过对DELLA蛋白功能结构域的进一步分析,作者还发现其中的LZ结构域对于DELLA蛋白的稳定性调控和生理活性发挥都是必须的。 由于泛素-蛋白酶体途径依赖的蛋白降解过程广泛地参与到各类植物激素的信号调控中, 本文利用该体外系统对DELLA蛋白降解的分析也可以为其他通路中重要的蛋白因子降解机理的研究提供新的思路和手段。(生物谷Bioon.com)
生物谷推荐原始出处:
Plant Cell Advance Online Publication August 28, 2009; 10.1105/tpc.108.065433
Biochemical Insights on Degradation of Arabidopsis DELLA Proteins Gained From a Cell-Free Assay System
Feng Wang 1, Danmeng Zhu 2, Xi Huang 1, Shuang Li 1, Yinan Gong 1, Qinfang Yao 3, Xiangdong Fu 3, Liu-Min Fan 4, and Xing Wang Deng 2*
1 National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China; College of Life Sciences, Beijing Normal University, Beijing 100875, China
2 National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China; Peking-Yale Joint Center for Plant Molecular Genetics and Agro-Biotechnology, National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
3 State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
4 Peking-Yale Joint Center for Plant Molecular Genetics and Agro-Biotechnology, National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
The phytohormone gibberellic acid (GA) regulates diverse aspects of plant growth and development. GA responses are triggered by the degradation of DELLA proteins, which function as repressors in GA signaling pathways. Recent studies in Arabidopsis thaliana and rice (Oryza sativa) have implied that the degradation of DELLA proteins occurred via the ubiquitin-proteasome system. Here, we developed an Arabidopsis cell-free system to recapitulate DELLA protein degradation in vitro. Using this cell-free system, we documented that Lys-29 of ubiquitin is the major site for ubiquitin chain formation to mediate DELLA protein degradation. We also confirmed the specific roles of GA receptors and multisubunit E3 ligase components in regulating DELLA protein degradation. In addition, blocking DELLA degradation with a PP1/PP2A phosphatase inhibitor in our cell-free assay suggested that degradation of DELLA proteins required protein Ser/Thr dephosphorylation activity. Furthermore, our data revealed that the LZ domain of Arabidopsis DELLA proteins is essential for both their stability and activity. Thus, our in vitro degradation system provides biochemical insights into the regulation of DELLA protein degradation. This in vitro assay system could be widely adapted for dissecting cellular signaling pathways in which regulated proteolysis is a key recurrent theme.