Abstract：
Functions of the SKP1-CUL1-F box (SCF) ubiquitin E3 ligases are essential in plants. The F box proteins (FBPs) are substrate receptors that recruit substrates and assemble an active SCF complex, but the regulatory mechanism underlying the FBPs binding to CUL1 to activate the SCF cycle is not fully understood. We show that Arabidopsis csn1-10 is defective in SCFEBF1-mediated PIF3 degradation during de-etiolation, due to impaired association of EBF1 with CUL1 in csn1-10. EBF1 preferentially associates with un-neddylated CUL1 that is deficient in csn1-10 and the EBF1-CUL1 binding is rescued by the neddylation inhibitor MLN4924. Furthermore, we identify a subset of FBPs with impaired binding to CUL1 in csn1-10, indicating their assembly to form SCF complexes may depend on COP9 signalosome (CSN)-mediated deneddylation of CUL1. This study reports that a key role of CSN-mediated CULLIN deneddylation is to gate the binding of the FBP-substrate module to CUL1, thus initiating the SCF cycle of substrate ubiquitination.
摘要：
SKP1-CUL1-F盒(SCF)泛素E3连接酶的功能在植物中是必需的。F盒蛋白（FBP）是底物受体，募集底物并组装活性SCF复合物，但FBP与CUL1结合激活SCF循环的调节机制尚不完全清楚。我们表明拟南芥csn1-10在去黄化过程中在SCFEBF1介导的PIF3降解中是有缺陷的，由于CSN1-10中EBF1与CUL1的关联受损。EBF1优先与在csn1-10中缺乏的未neddylatedCUL1缔合，并且通过neddylation抑制剂MLN4924挽救了EBF1-CUL1结合。此外，我们在csn1-10中鉴定了与CUL1结合受损的FBP子集，表明它们组装形成SCF复合物可能取决于COP9信号体（CSN）介导的CUL1去甲基化。这项研究报道，CSN介导的CULLIN去乙酰化的关键作用是控制FBP底物模块与CUL1的结合，从而启动底物泛素化的SCF循环。
