QUATERNARY STRUCTURE OF INFLUENZA-VIRUS HEMAGGLUTININ AFTER ACID TREATMENT
QUATERNARY STRUCTURE OF INFLUENZA-VIRUS HEMAGGLUTININ AFTER ACID TREATMENT
复制标题
DOI：
10.1128/jvi.60.3.833-839.1986
复制
发表时间：
1986-12-01
影响因子：
5.4
通讯作者：
HELENIUS, A
中科院分区：
文献类型：
--
作者：
DOMS, RW;HELENIUS, A
血凝素 (HA) 是流感病毒的一种三聚体刺突糖蛋白，在病毒进入过程中介导病毒包膜和内体膜之间的融合。低 pH 值会引发融合，从而导致蛋白质发生不可逆的构象变化。几项研究表明，在这种改变过程中，沿着三聚体界面的亚基间接触可能会被破坏。为了确定 HA 是否由于构象变化而解离成单个亚基，我们在 Triton X-100 存在的情况下使用了速度梯度沉降。我们还测定了酸处理的 HA 对十二烷基硫酸钠解离的抵抗力，这是 HA 三聚体的一种特性。在 pH 7.0 时，分离出的 HA 以 9S 三聚体形式沉淀，并在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳后给出特征性三聚体模式。酸化后，HA 保持三聚体状态，无论其是否以完整病毒颗粒或溶解形式暴露于酸。只有当非常低浓度的 HA 被酸化时，才会有一部分解离二聚体和单体。相比之下，HA (BHA) 的水溶性胞外域片段在各种条件下很容易解离。负应变电子显微镜支持这样的观点，即病毒颗粒中的 HA 分子在酸化时不会解离，并且可能在病毒膜平面上形成更大的寡聚结构。总而言之，结果表明三聚体HA或其高级结构在酸诱导的融合反应中具有活性。此外，结果强调了 HA 跨膜锚在防止三聚体解离中的作用。
Hemagglutinin (HA), a trimeric spike glycoprotein of influenza virus, mediates fusion between the viral envelope and the membrane of an endosome during virus entry. Fusion is triggered by low pH, which induces an irreversible conformational change in the protein. Several studies have indicated that intersubunit contacts along the trimer interfaces may be broken during this alteration. To determine whether HA dissociates into individual subunits as a consequence of the conformational change, we used velocity gradient sedimentation in the presence of Triton X-100. We also determined the resistance of acid-treated HA to dissociation by sodium dodecyl sulfate, a property of the HA trimer. At pH 7.0, isolated HA sedimented as a 9S trimer and gave the characteristic trimer pattern after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After acidification the HA remained trimeric irrespective of whether it was exposed to acid in intact virus particles or in solubilized form. Only when very low concentrations of HA were acidified did a fraction dissociate the dimers and monomers. In contrast, the water-soluble ectodomain fragment of HA (BHA) readily dissociated under a variety of conditions. Negative-strain electron microscopy supported the notion that HA molecules in virus particles do not dissociate upon acidification and may form larger oligomeric structures in the plane of the viral membrane. Taken together, the results suggested that it is the trimeric HA, or higher-order structures thereof, that are active in the acid-induced fusion reaction. Further, the results emphasized the role of the transmembrane anchors of HA in preventing dissociation of the trimer.