PDF(Pubmed)
Abstract：
The conserved eight-subunit COP9 signalosome (CSN) is required for multicellular fungal development. The CSN deneddylase cooperates with the Cand1 exchange factor to control replacements of E3 ubiquitin cullin RING ligase receptors, providing specificity to eukaryotic protein degradation. Aspergillus nidulans CSN assembles through a heptameric pre-CSN, which is activated by integration of the catalytic CsnE deneddylase. Combined genetic and biochemical approaches provided the assembly choreography within a eukaryotic cell for native fungal CSN. Interactomes of functional GFP-Csn subunit fusions in pre-CSN deficient fungal strains were compared by affinity purifications and mass spectrometry. Two distinct heterotrimeric CSN subcomplexes were identified as pre-CSN assembly intermediates. CsnA-C-H and CsnD-F-G form independently of CsnB, which connects the heterotrimers to a heptamer and enables subsequent integration of CsnE to form the enzymatically active CSN complex. Surveillance mechanisms control accurate Csn subunit amounts and correct cellular localization for sequential assembly since deprivation of Csn subunits changes the abundance and location of remaining Csn subunits.
摘要：
保守的八亚基COP9信号体（CSN）是多细胞真菌发育所必需的。CSNdeneddase与Cand1交换因子合作以控制E3泛素cullinRING连接酶受体的替换，为真核蛋白质降解提供特异性。构巢曲霉CSN通过七聚体前CSN组装，其通过催化CsnE脱乙酰酶的整合而活化。结合的遗传和生化方法为天然真菌CSN提供了真核细胞内的组装编排。通过亲和纯化和质谱法比较了CSN缺陷前真菌菌株中功能性GFP-Csn亚基融合体的相互作用。两种不同的异三聚体CSN亚复合物被鉴定为前CSN组装中间体。CsnA-C-H和CsnD-F-G独立于CsnB形成，其将异源三聚体连接至七聚体并使得CsnE能够随后整合以形成酶活性CSN复合物。监视机制控制准确的Csn亚基量并正确的细胞定位以进行顺序组装，因为Csn亚基的剥夺会改变剩余Csn亚基的丰度和位置。
