2009年8月28日, 北京生命科學(xué)研究所鄧興旺實(shí)驗(yàn)室在The Plant Cell雜志上在線發(fā)表題為 ”Biochemical Insights on Degradation of Arabidopsis DELLA Proteins Gained From A Cell-free Assay System”的文章,。 該文章通過(guò)建立體外降解系統(tǒng), 對(duì)GA調(diào)控的DELLA蛋白的降解機(jī)理進(jìn)行了深入的生化分析,。
DELLA蛋白作為GA信號(hào)傳導(dǎo)途徑中的主要負(fù)調(diào)控因子, 同時(shí)也是整合其他植物激素或環(huán)境信號(hào)的樞紐蛋白來(lái)調(diào)節(jié)植物的生長(zhǎng)發(fā)育過(guò)程。植物體接受GA信號(hào)后, 通過(guò)泛素-蛋白酶體途徑降解DELLA蛋白來(lái)解除其對(duì)生長(zhǎng)的抑制作用,。 該文章通過(guò)建立DELLA蛋白體外降解體系對(duì)其降解機(jī)理進(jìn)行分析,。 利用該體外降解系統(tǒng), 作者驗(yàn)證了GA受體和SCF泛素連接酶復(fù)合體在DELLA蛋白降解中的重要作用。并且,，發(fā)現(xiàn)了泛素分子的第29位賴氨酸可能是介導(dǎo)DELLA蛋白降解中泛素鏈形成的一個(gè)重要位點(diǎn), 與經(jīng)典的第48位賴氨酸起功能協(xié)同作用,。 通過(guò)對(duì)DELLA蛋白功能結(jié)構(gòu)域的進(jìn)一步分析，作者還發(fā)現(xiàn)其中的LZ結(jié)構(gòu)域?qū)τ贒ELLA蛋白的穩(wěn)定性調(diào)控和生理活性發(fā)揮都是必須的,。 由于泛素-蛋白酶體途徑依賴的蛋白降解過(guò)程廣泛地參與到各類植物激素的信號(hào)調(diào)控中, 本文利用該體外系統(tǒng)對(duì)DELLA蛋白降解的分析也可以為其他通路中重要的蛋白因子降解機(jī)理的研究提供新的思路和手段,。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
