The Gag-like protein of the yeast Ty1 retrotransposon contains a nucleic acid chaperone domain analogous to retroviral nucleocapsid proteins
The Gag-like protein of the yeast Ty1 retrotransposon contains a nucleic acid chaperone domain analogous to retroviral nucleocapsid proteins
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DOI：
10.1074/jbc.m001371200
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发表时间：
2000-06-23
影响因子：
4.8
通讯作者：
Darlix, JL
中科院分区：
文献类型：
--
作者：
Cristofari, G;Ficheux, D;Darlix, JL
逆转录病毒和逆转录转座子的逆转录过程发生在病毒或病毒样颗粒的核核结构中。在逆转录病毒中，核核的主要蛋白质是核衣壳蛋白（NC 蛋白），它源自 GAG 的 C 末端区域。逆转录病毒 NC 蛋白由两侧为碱性残基的一个或两个 CCHC 锌指组成，并具有病毒复制所必需的核酸伴侣和匹配特性。有趣的是，包括泡沫病毒在内的许多逆转录因子的 GAG 蛋白不具备逆转录病毒 GAG 的特征，特别是缺乏典型的 NC 蛋白。为了寻找此类逆转录元件中的核酸伴侣活性，我们使用酵母 Ty1 逆转录转座子作为模型系统。结果表明，Ty1 GAG C 端区域含有一个核酸伴侣结构域，能够促进引物 tRNA(i)(Met) 与多部分引物结合位点退火、Ty1 RNA 二聚化和逆转录启动，而且 Ty1 RNA 二聚化似乎是由 tRNA(i)(Met) 介导的，其方式与 Ty3 相似，但与逆转录病毒 RNA 不同。这些发现表明核酸伴侣蛋白可能是逆转录酶的一般辅助因子。
The reverse transcription process for retroviruses and retrotransposons takes place in a nucleocore structure in the virus or virus-like particle. In retroviruses the major protein of the nucleocore is the nucleocapsid protein (NC protein), which derives from the C-terminal region of GAG. Retroviral NC proteins are formed of either one or two CCHC zinc finger(s) flanked by basic residues and have nucleic acid chaperone and matchmaker properties essential for virus replication. Interestingly, the GAG protein of a number of retroelements including Spumaviruses does not possess the hallmarks of retroviral GAGs and in particular lacks a canonical NC protein. In an attempt to search for a nucleic acid chaperone activity in this class of retroelements we used the yeast Ty1 retrotransposon as a model system. Results shows that the C-terminal region of Ty1 GAG contains a nucleic acid chaperone domain capable of promoting the annealing of primer tRNA(i)(Met) to the multipartite primer binding site, Ty1 RNA dimerization and initiation of reverse transcription, Moreover Ty1 RNA dimerization, in a manner similar to Ty3 but unlike retroviral RNAs, appears to be mediated by tRNA(i)(Met). These findings suggest that nucleic acid chaperone proteins probably are general co-factors for reverse transcriptases.