Sequential Duplications of an Ancient Member of the DnaJ-Family Expanded the Functional Chaperone Network in the Eukaryotic Cytosol
Sequential Duplications of an Ancient Member of the DnaJ-Family Expanded the Functional Chaperone Network in the Eukaryotic Cytosol
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DOI：
10.1093/molbev/mst008
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发表时间：
2013-05-01
影响因子：
10.7
通讯作者：
Craig, Elizabeth A.
中科院分区：
文献类型：
--
作者：
Sahi, Chandan;Kominek, Jacek;Craig, Elizabeth A.
在真核生物中，基于 Hsp70 的伴侣机制在其序列、结构和生化作用机制方面表现出潜在的统一性，同时在无数的细胞过程中发挥作用。在很大程度上，这种非凡的功能多功能性源自单个 Hsp70 与一系列 J 蛋白辅助伴侣相互作用形成功能性伴侣网络的能力。在 J 蛋白中，DnaJ 型是最普遍的，存在于所有三个界以及真核细胞的几个不同区室中。然而，由于这些古老的 DnaJ 型蛋白质在真核系统发育的基础上发生了分化，因此人们对它们多样化的进化基础以及伴侣网络的功能扩展知之甚少。在这里，我们报告了酿酒酵母胞质 DnaJ 家族的两个最新成员 Xdj1 和 Apj1 的进化和实验分析结果，它们是通过子囊菌中古代 YDJ1 的连续复制而出现的。序列比较和分子建模表明，Xdj1 和 Apj1 都保持与多功能 Ydj1 相似的结构域组织。然而，尽管有这些相似之处，Xdj1 和 Apj1 都进化出了高度专业化的功能。 Xdj1 在蛋白质从细胞质转移到线粒体的过程中发挥着独特的作用。 Apj1 的特殊作用与 sumolyated 蛋白质的降解有关。这些数据共同提供了第一个清晰的例子，说明辅助伴侣复制品进化出专门的功能，允许伴侣功能网络的扩展，同时保持其亲代基因的整体结构组织。
Across eukaryotes, Hsp70-based chaperone machineries display an underlying unity in their sequence, structure, and biochemical mechanism of action, while working in a myriad of cellular processes. In good part, this extraordinary functional versatility is derived from the ability of a single Hsp70 to interact with an array of J-protein cochaperones to form a functional chaperone network. Among J-proteins, the DnaJ-type is the most prevalent, being present in all three kingdoms and in several different compartments of eukaryotic cells. However, because these ancient DnaJ-type proteins diverged at the base of the eukaryotic phylogeny, little is understood about the evolutionary basis of their diversification and thus the functional expansion of the chaperone network. Here, we report results of evolutionary and experimental analyses of two more recent members of the cytosolic DnaJ family of Saccharomyces cerevisiae, Xdj1 and Apj1, which emerged by sequential duplications of the ancient YDJ1 in Ascomycota. Sequence comparison and molecular modeling revealed that both Xdj1 and Apj1 maintained a domain organization similar to that of multifunctional Ydj1. However, despite these similarities, both Xdj1 and Apj1 evolved highly specialized functions. Xdj1 plays a unique role in the translocation of proteins from the cytosol into mitochondria. Apj1's specialized role is related to degradation of sumolyated proteins. Together these data provide the first clear example of cochaperone duplicates that evolved specialized functions, allowing expansion of the chaperone functional network, while maintaining the overall structural organization of their parental gene.