CSN1 N-terminal-dependent activity is required for Arabidopsis development but not for Rub1/Nedd8 deconjugation of cullins: a structure-function study of CSN1 subunit of COP9 signalosome.
CSN1 N-terminal-dependent activity is required for Arabidopsis development but not for Rub1/Nedd8 deconjugation of cullins: a structure-function study of CSN1 subunit of COP9 signalosome.
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DOI：
10.1091/mbc.01-08-0427
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发表时间：
2002-02
影响因子：
3.3
通讯作者：
Xiping Wang;D. Kang;S. Feng;G. Serino;C. Schwechheimer;N. Wei
中科院分区：
文献类型：
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作者：
Xiping Wang;D. Kang;S. Feng;G. Serino;C. Schwechheimer;N. Wei
COP9信号体（CSN）是拟南芥发育所必需的多功能蛋白复合物。其功能之一是促进Rub1/Nedd8从Skp1-cullin-F-box泛素连接酶的cullin亚基上解偶联。对于其8个亚基在去髓鞘化或CSN的任何生理功能中的具体作用知之甚少。在缺少CSN1 （fus6突变体）的情况下，拟南芥CSN复合物无法组装，这使得多个CSN亚基不稳定，并与CSN1的缺失一起导致了fus6的表型。为了区分CSN1的特异性功能，我们试图用缺失或点突变形式的CSN1在fus6中表达为转基因来挽救复合物的形成。我们发现CSN1的中心结构域对复杂的组装至关重要，而c端结构域具有支持作用。通过表达包含结构信息但缺乏假定的位于N端功能域的C231片段，我们挽救了复合物的形成并恢复了cullins （fus6/C231）上的Rub1/Nedd8解偶联活性。然而，fus6/C231在苗期表现出多效性，包括光形态发生缺陷和生长停滞。我们得出结论，CSN1 n -末端结构域不是cullins的Rub1/Nedd8解耦活性所必需的，但它对植物发育所必需的CSN功能有重要作用。
The COP9 signalosome (CSN) is a multifunctional protein complex essential for arabidopsis development. One of its functions is to promote Rub1/Nedd8 deconjugation from the cullin subunit of the Skp1-cullin-F-box ubiquitin ligase. Little is known about the specific role of its eight subunits in deneddylation or any of the physiological functions of CSN. In the absence of CSN1 (the fus6 mutant), arabidopsis CSN complex cannot assemble, which destabilizes multiple CSN subunits and contributes, together with the loss of CSN1, to the phenotype of fus6. To distinguish CSN1-specific functions, we attempted to rescue the complex formation with deletion or point-mutation forms of CSN1 expressed as transgenes in fus6. We show that the central domain of CSN1 is critical for complex assembly, whereas the C-terminal domain has a supporting role. By expressing the C231 fragment, which contains the structural information but lacks the presumed functional domain located at the N terminus, we have rescued the complex formation and restored the Rub1/Nedd8 deconjugation activity on cullins (fus6/C231). Nonetheless, fus6/C231 exhibits pleiotropic phenotype, including photomorphogenic defects and growth arrest at seedling stage. We conclude that CSN1 N-terminal domain is not required for the Rub1/Nedd8 deconjugation activity of cullins, but contributes to a significant aspect of CSN functions that are essential for plant development.