Szepanski S, Veit M, Pleschka S, Klenk H D, Schmidt M F, Herrler G
Institut für Virologie, Philipps-Universität Marburg, Germany.
J Gen Virol. 1994 May;75 ( Pt 5):1023-30. doi: 10.1099/0022-1317-75-5-1023.
The post-translational processing of the influenza C virus glycoprotein HEF was analysed. In cells infected with influenza C virus, HEF protein is synthesized as a glycosylated 80K polypeptide. A post-translational conformational rearrangement involving the formation of intramolecular disulphide bonds results in a decrease in its electrophoretic mobility. Therefore, SDS-PAGE under non-reducing conditions suggests an Mr of about 100K, whereas under reducing conditions an 80K protein is observed which is in accordance with the sequence data. The 100K form was detected 10 min after synthesis of HEF, and transport to the cell surface took about 60 min. This result indicates that the conformational change presumably occurs in the endoplasmic reticulum. A difference in post-translational processing was observed when the HEF gene was expressed in the absence of other influenza C virus genes. In cells infected with recombinant simian virus 40, the 80K precursor was synthesized, but this protein was neither converted to the 100K form nor transported to the cell surface. Deletion of the short cytoplasmic tail of HEF (Arg-Thr-Lys) or replacement of the two basic amino acids by hydrophobic (Ile) or acidic residues (Glu) resulted in HEF protein which was partially converted to the 100K form. Influenza C virus glycoprotein obtained after transient expression of the HEF gene using the vaccinia virus system was completely converted to the 100K form. However, in neither expression system was HEF transported to the cell surface. The possibility is discussed that the interaction of HEF with another viral protein is required for the post-translational folding and transport of this glycoprotein. The M protein of influenza C virus is suggested as a candidate for the chaperone which might interact with the cytoplasmic tail of HEF.
对丙型流感病毒糖蛋白HEF的翻译后加工过程进行了分析。在感染丙型流感病毒的细胞中，HEF蛋白作为一种糖基化的80K多肽被合成。涉及分子内二硫键形成的翻译后构象重排导致其电泳迁移率降低。因此，在非还原条件下进行的SDS-PAGE显示其分子量约为100K，而在还原条件下观察到的是80K的蛋白，这与序列数据一致。HEF合成后10分钟即可检测到100K的形式，而运输到细胞表面大约需要60分钟。这一结果表明构象变化可能发生在内质网中。当HEF基因在没有其他丙型流感病毒基因的情况下表达时，观察到翻译后加工存在差异。在感染重组猿猴病毒40的细胞中，合成了80K的前体蛋白，但该蛋白既没有转化为100K的形式，也没有运输到细胞表面。删除HEF的短细胞质尾巴（精氨酸-苏氨酸-赖氨酸）或将两个碱性氨基酸替换为疏水（异亮氨酸）或酸性残基（谷氨酸）会导致HEF蛋白部分转化为100K的形式。使用痘苗病毒系统瞬时表达HEF基因后获得的丙型流感病毒糖蛋白完全转化为100K的形式。然而，在这两种表达系统中，HEF均未运输到细胞表面。文中讨论了一种可能性，即HEF与另一种病毒蛋白的相互作用是该糖蛋白翻译后折叠和运输所必需的。丙型流感病毒的M蛋白被认为是可能与HEF细胞质尾巴相互作用的伴侣蛋白候选者。
