Intracellular topology and epitope shielding of poliovirus 3A protein
Intracellular topology and epitope shielding of poliovirus 3A protein
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DOI：
10.1128/jvi.78.11.5973-5982.2004
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发表时间：
2004-06-01
影响因子：
5.4
通讯作者：
Kirkegaard, K
中科院分区：
文献类型：
--
作者：
Choe, SS;Kirkegaard, K
脊髓灰质炎病毒RNA复制复合物包括在重排的细胞内膜的细胞质表面上组装的多种病毒和可能的细胞蛋白。病毒蛋白3A和3AB在脊髓灰质炎病毒复制周期中执行几种功能，包括在重排膜、将病毒聚合酶锚定到这些膜、抑制宿主蛋白分泌以及可能为RNA合成提供3B蛋白引物中的重要作用。在脊髓灰质炎病毒感染期间，与在不存在其他脊髓灰质炎病毒蛋白的情况下表达的3A蛋白相比，含3A蛋白的氨基末端表位的免疫荧光信号被显著屏蔽。这不是由于所有或一个子集的3A-含有多肽的管腔方向，如所示的免疫荧光后，差分透化和蛋白水解实验。在野生型脊髓灰质炎病毒感染的细胞中，3A表位的屏蔽比在含有邻近3AB结合位点的3D聚合酶编码区中的突变的温度敏感性突变病毒的细胞中更明显。因此，很可能脊髓灰质炎病毒RNA依赖性RNA聚合酶的直接结合封闭了RNA复制复合物中含3A多肽的氨基末端。
The poliovirus RNA replication complex comprises multiple viral and possibly cellular proteins assembled on the cytoplasmic surface of rearranged intracellular membranes. Viral proteins 3A and 3AB perform several functions during the poliovirus replicative cycle, including significant roles in rearranging membranes, anchoring the viral polymerase to these membranes, inhibiting host protein secretion, and possibly providing the 3B protein primer for RNA synthesis. During poliovirus infection, the immunofluorescence signal of an amino-terminal epitope of 3A-containing proteins is markedly shielded compared to 3A protein expressed in the absence of other poliovirus proteins. This is not due to luminal orientation of all or a subset of the 3A-containing polypeptides, as shown by immunofluorescence following differential permeabilization and proteolysis experiments. Shielding of the 3A epitope is more pronounced in cells infected with wild-type poliovirus than in cells with temperature-sensitive mutant virus that contains a mutation in the 3D polymerase coding region adjacent to the 3AB binding site. Therefore, it is likely that direct binding of the poliovirus RNA-dependent RNA polymerase occludes the amino terminus of 3A-containing polypeptides in the RNA replication complex.