The capsid protein of beak and feather disease virus binds to the viral DNA and is responsible for transporting the replication-associated protein into the nucleus
The capsid protein of beak and feather disease virus binds to the viral DNA and is responsible for transporting the replication-associated protein into the nucleus
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DOI：
10.1128/jvi.02559-05
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发表时间：
2006-07-01
影响因子：
5.4
通讯作者：
Rybicki, Edward P.
中科院分区：
文献类型：
--
作者：
Heath, Livio;Williamson, Anna-Lise;Rybicki, Edward P.
圆环病毒缺乏自主 DNA 聚合酶，依赖于宿主细胞的复制机制进行 DNA 从头合成。因此，病毒 DNA 在复制之前需要穿过质膜和核膜。在这里，我们报告了昆虫细胞系统中通过重组杆状病毒表达的喙羽病病毒（BFDV）衣壳蛋白（CP）和复制相关蛋白（Rep）的亚细胞分布，并检验了 CP 负责跨核膜运输病毒基因组和 Rep 的假设。发现 BFDV CP 的细胞内定位是由位于蛋白质 N 末端残基 16 和 56 之间的三个部分重叠的二分核定位信号 (NLS) 引导的。此外，DNA 结合区域也被映射到该蛋白质的 N 末端，并且位于包含三个假定 NLS 的区域内。 CP 结合 DNA 的能力，加上该蛋白的亲核性质，强烈表明它可能负责病毒基因组的核靶向。有趣的是，虽然 Rep 在昆虫细胞中单独表达仅限于细胞质，但与 CP 共表达改变了 Rep 在细胞核中的亚细胞定位，强烈表明与 CP 的相互作用促进 Rep 移动到细胞核中。
Circoviruses lack an autonomous DNA polymerase and are dependent on the replication machinery of the host cell for de novo DNA synthesis. Accordingly, the viral DNA needs to cross both the plasma membrane and the nuclear envelope before replication can occur. Here we report on the subcellular distribution of the beak and feather disease virus (BFDV) capsid protein (CP) and replication-associated protein (Rep) expressed via recombinant baculoviruses in an insect cell system and test the hypothesis that the CP is responsible for transporting the viral genome, as well as Rep, across the nuclear envelope. The intracellular localization of the BFDV CP was found to be directed by three partially overlapping bipartite nuclear localization signals (NLSs) situated between residues 16 and 56 at the N terminus of the protein. Moreover, a DNA binding region was also mapped to the N terminus of the protein and falls within the region containing the three putative NLSs. The ability of CP to bind DNA, coupled with the karyophilic nature of this protein, strongly suggests that it may be responsible for nuclear targeting of the viral genome. Interestingly, whereas Rep expressed on its own in insect cells is restricted to the cytoplasm, coexpression with CP alters the subcellular localization of Rep to the nucleus, strongly suggesting that an interaction with CP facilitates movement of Rep into the nucleus.