DnaJ/hsp40 chaperone domain of SV40 large T antigen promotes efficient viral DNA replication
DnaJ/hsp40 chaperone domain of SV40 large T antigen promotes efficient viral DNA replication
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DOI：
10.1101/gad.11.9.1098
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发表时间：
1997-05-01
影响因子：
10.5
通讯作者：
DeCaprio, JA
中科院分区：
文献类型：
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作者：
Campbell, KS;Mullane, KP;DeCaprio, JA
SV40大肿瘤抗原(Tag)的氨基端结构域是病毒DNA高效复制所必需的。然而，与这个结构域相关的生化活性仍然不清楚。我们在这里证明了TAG的氨基末端结构域与DNAJ/Hsp40分子伴侣的J-结构域具有功能同源性。DNAJ蛋白通过调节70-kD热休克蛋白家族的一个成员的活性而发挥辅助因子的作用。遗传分析表明，Tag的氨基末端序列包含一个新的T结构域，该结构域介导了与组成性表达的hsc70的特定相互作用，并表明T结构域也是在体内有效复制病毒DNA所必需的。此外，我们还证明了两个人DNAJ同源物HSJ1或DNAJ2的T结构域可以在功能上替代TAG的氨基末端来促进病毒DNA的复制。综上所述，我们的发现表明，Tag使用其T结构域来支持SV40 DNA复制，其方式与噬菌体Lambda使用大肠杆菌DNAJ进行DNA复制的方式惊人地相似。然而，Tag已经进化出一种更有效的DNA复制策略，通过固有的T结构域直接与伴侣伴侣蛋白结合。我们的观察为伴侣蛋白在真核DNA复制过程中的作用提供了证据。
The amino-terminal domain of SV40 large tumor antigen (TAg) is required for efficient viral DNA replication. However, the biochemical activity associated with this domain has remained obscure. We show here that the amino-terminal domain of TAg shares functional homology with the J-domain of DnaJ/hsp40 molecular chaperones. DnaJ proteins function as cofactors by regulating the activity of a member of the 70-kD heat shock protein family. Genetic analyses demonstrated that amino-terminal sequences of TAg comprise a novel T-domain that mediates a specific interaction with the constitutively expressed hsc70 and show that the T-domain is also required for efficient viral DNA replication in vivo. Furthermore, we demonstrated that the T-domain of two human DnaJ homologs, HSJ1 or DNAJ2, could substitute functionally for the amino-terminus of TAg in promoting viral DNA replication. Together, our findings suggest that TAg uses its T-domain to support SV40 DNA replication in a manner that is strikingly similar to the use of Escherichia coli DnaJ by bacteriophage lambda in DNA replication. However, TAg has evolved a more efficient strategy of DNA replication through an intrinsic T-domain to associate directly with a partner chaperone protein. Our observations provide evidence of a role for chaperone proteins in the process of eukaryotic DNA replication.