Inhibition of endoplasmic reticulum-to-Golgi traffic by poliovirus protein 3A: Genetic and ultrastructural analysis
Inhibition of endoplasmic reticulum-to-Golgi traffic by poliovirus protein 3A: Genetic and ultrastructural analysis
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DOI：
10.1128/jvi.71.12.9054-9064.1997
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发表时间：
1997-12-01
影响因子：
5.4
通讯作者：
Kirkegaard, K
中科院分区：
文献类型：
--
作者：
Doedens, JR;Giddings, TH;Kirkegaard, K
脊髓灰质炎病毒蛋白3A，长度仅为87个氨基酸，是哺乳动物细胞中蛋白质分泌的有效抑制剂，阻断蛋白质从内质网（ER）到高尔基复合体的顺行运输。病毒蛋白3A在阻断蛋白分泌方面的功能对蛋白N末端附近的突变极其敏感。前10个氨基酸的缺失或氨基酸15和16之间的单个氨基酸的插入（导致脊髓灰质炎病毒RNA复制中的冷敏感缺陷的突变）消除了蛋白分泌的抑制，尽管表达了野生型量的突变蛋白。免疫荧光显微镜和免疫电子显微镜表明，3A蛋白，表达在其他病毒蛋白的情况下，共定位，与来自ER的膜。3A相对于ER膜的精确拓扑结构尚不清楚，但它可能与ER的胞质表面相关。虽然已经报道了翻译提取物中3A的糖基化，但我们表明，在细胞蛋白糖基化被抑制的条件下，衣霉素对脊髓灰质炎病毒生长没有影响，因此，3A的糖基化在病毒复制周期中不起功能性作用。电子显微镜显示，在3A蛋白的存在下，ER显着扩张，积累的囊泡和ER衍生膜的肿胀的情况下，认为ER到高尔基体的交通在囊泡形成或出芽的步骤中被抑制。
Poliovirus protein 3A, only 87 amino acids in length, is a potent inhibitor of protein secretion in mammalian cells, blocking anterograde protein traffic from the endoplasmic reticulum (ER) to the Golgi complex. The function of viral protein 3A in blocking protein secretion is extremely sensitive to mutations near the N terminus of the protein, Deletion of the first 10 amino acids or insertion of a single amino acid between amino acids 15 and 16, a mutation that causes a cold-sensitive defect in poliovirus RNA replication, abrogates the inhibition of protein secretion although wild-type amounts of the mutant proteins are expressed. Immunofluorescence light microscopy and immunoelectron microscopy demonstrate that 3A protein, expressed in the absence of other viral proteins, colocalizes, with membranes derived from the ER. The precise topology of 3A with respect to ER membranes is not known, but it is likely to be associated with the cytosolic surface of the ER. Although the glycosylation of 3A in translation extracts has been reported, we show that tunicamycin, under conditions in which glycosylation of cellular proteins is inhibited, has no effect on poliovirus growth, Therefore, glycosylation of 3A plays no functional role in the viral replicative cycle. Electron microscopy reveals that the ER dilates dramatically in the presence of 3A protein, The absence of accumulated vesicles and the swelling of the ER-derived membranes argues that ER-to-Golgi traffic is inhibited at the step of vesicle formation or budding from the ER.