Key Laboratory of Biotechnology and Crop Quality Improvement of Ministry of Agriculture, Biotechnology Research Center, Southwest University, Chongqing 400716, China; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Plant Sci. 2014 Jul;224:54-61. doi: 10.1016/j.plantsci.2014.04.001. Epub 2014 Apr 8.
CSN5 is a subunit of the COP9 signalosome (CSN) and carries the metallo-protease catalytic center for the complex. This highly conserved gene has been a subject of intense research in part because human Csn5 (Jab1) has been tightly linked to cancer. We briefly summarize recent research advances on the structure and mechanisms of the CSN in general, and then focus on the Arabidopsis CSN5 genes and their products, AtCSN5A and AtCSN5B. We also briefly discuss CSN6 genes, which are closely related share many similarities to CSN5. CSN5 and CSN6 genes are duplicated in mustard family of plants as well as in several plant species that have no phylogenetic correlation. Sequence homology comparison further suggests that at least some of the duplication events occurred independently. We review and analyze the phenotypic and expression differences of the two CSN5 genes in Arabidopsis, and suggest that they play overlapping as well as specialized roles in plant development. Arabidopsis CSN5 protein sequences are more similar to those of complex organisms such as humans than to yeasts and unicellular alga, suggesting that the structure and mechanism of Arabidopsis CSN5 likely resembles more to those of human than to yeast. We argue that possession of two different isoforms of CSN5s gives Arabidopsis a unique advantage as a genetic model of CSN5 to dissect the multifaceted functions and mechanistic versatilities of this important cellular regulator.
CSN5 是 COP9 信号体（CSN）的一个亚基，携带该复合物的金属蛋白酶催化中心。这个高度保守的基因一直是研究的热点，部分原因是人类 Csn5（Jab1）与癌症密切相关。我们简要总结了 CSN 的结构和机制的最新研究进展，然后重点介绍拟南芥 CSN5 基因及其产物 AtCSN5A 和 AtCSN5B。我们还简要讨论了与 CSN5 密切相关的 CSN6 基因，它们具有许多相似之处。CSN5 和 CSN6 基因在芥菜科植物以及与其他植物没有系统发育关系的几种植物中都有复制。序列同源性比较进一步表明，至少有一些复制事件是独立发生的。我们对拟南芥中两个 CSN5 基因的表型和表达差异进行了综述和分析，并提出它们在植物发育中发挥重叠和专门作用。拟南芥 CSN5 蛋白序列与人类等复杂生物的序列更为相似，而与酵母和单细胞藻类的序列相似性较低，这表明拟南芥 CSN5 的结构和机制可能与人类的更为相似，而不是酵母的。我们认为，拟南芥拥有两种不同的 CSN5 同工型，这使它成为 CSN5 的遗传模型，具有独特的优势，可以解析这个重要的细胞调节因子的多方面功能和机制多样性。
