A novel sorting signal for intracellular localization is present in the S protein of a porcine coronavirus but absent from severe acute respiratory syndrome-associated coronavirus
A novel sorting signal for intracellular localization is present in the S protein of a porcine coronavirus but absent from severe acute respiratory syndrome-associated coronavirus
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DOI：
10.1074/jbc.m407233200
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发表时间：
2004-10-15
影响因子：
4.8
通讯作者：
Herrler, G
中科院分区：
文献类型：
--
作者：
Schwegmann-Wessels, C;Al-Falah, M;Herrler, G
冠状病毒（CoV）通过细胞内膜上的出芽过程成熟。在这里，我们表明，猪冠状病毒（传染性胃肠炎病毒）的主要表面蛋白S是不运输到细胞表面，但保留在细胞内。定点突变表明，细胞质尾部的酪氨酸依赖性信号（YXXI）对于S蛋白的细胞内定位至关重要。通过免疫荧光分析和表面生物素化，突变蛋白的表面表达是明显的。胞内保留的S蛋白只含有糖苷内切酶H-敏感的N-聚糖，而迁移到质膜获得的复杂类型的N-连接的寡糖的突变蛋白。相应的酪氨酸残基存在于其他动物冠状病毒的S蛋白的胞质尾部，但不存在于严重急性呼吸综合征（SARS）-冠状病毒的S蛋白的尾部。将SEPV胞质尾区的四肽改变为YEPI，导致SARS-CoV的S蛋白在胞内滞留。由于冠状病毒的S蛋白具有受体结合和融合活性，是中和抗体的主要靶点，S蛋白转运行为的差异表明SARS冠状病毒与其他冠状病毒在病毒宿主相互作用中的策略不同。
Coronaviruses (CoV) mature by a budding process at intracellular membranes. Here we showed that the major surface protein S of a porcine CoV ( transmissible gastroenteritis virus) is not transported to the cell surface but is retained intracellularly. Site-directed mutagenesis indicated that a tyrosine-dependent signal (YXXI) in the cytoplasmic tail is essential for intracellular localization of the S protein. Surface expression of mutant proteins was evident by immunofluorescence analysis and surface biotinylation. Intracellularly retained S proteins only contained endoglycosidase H-sensitive N-glycans, whereas mutant proteins that migrated to the plasma membrane acquired N-linked oligosaccharides of the complex type. Corresponding tyrosine residues are present in the cytoplasmic tails of the S proteins of other animal CoV but not in the tail portion of the S protein of severe acute respiratory syndrome (SARS)-CoV. Changing the SEPV tetrapeptide in the cytoplasmic tail to YEPI resulted in intracellular retention of the S protein of SARS-CoV. As the S proteins of CoV have receptor binding and fusion activities and are the main target of neutralizing antibodies, the differences in the transport behavior of the S proteins suggest different strategies in the virus host interactions between SARS-CoV and other coronaviruses.