Reversible merger of membranes at the early stage of influenza hemagglutinin-mediated fusion
Reversible merger of membranes at the early stage of influenza hemagglutinin-mediated fusion
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DOI：
10.1091/mbc.11.7.2359
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发表时间：
2000-07-01
影响因子：
3.3
通讯作者：
Chernomordik, LV
中科院分区：
文献类型：
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作者：
Leikina, E;Chernomordik, LV
流感病毒血凝素（HA）是一种原型融合蛋白，其介导的融合通常被检测为融合细胞之间的脂质和内容物混合。降低融合能力HA的表面密度抑制了这些高级融合表型，并使我们能够在生理温度下识别融合的早期阶段。虽然膜之间的脂质流动受到限制，接触的膜单层显然是短暂连接，检测到这种融合中间转化为完全融合后，治疗已知的不稳定hemifusion隔膜。这些可逆的连接在低pH值作用后10-20 min内消失，表明HA折叠释放的能量消散后，HA最终的低pH构象不支持膜合并。虽然性格活泼而缺乏脂质.在37 ℃下的混合将新鉴定的融合中间体与先前描述的在4 ℃下停滞的中间体区分开，两种中间体显然属于相同的限制性半融合（RH）结构家族。由于在生理温度下瞬时RH结构的形成与融合孔开放一样快，并且需要较少的HA，因此我们假设融合开始于多个RH位点的形成，其中只有少数位点随后演变为扩展的融合孔。
Fusion mediated by influenza hemagglutinin (HA), a prototype fusion protein, is commonly detected as lipid and content mixing between fusing cells. Decreasing the surface density of fusion-competent HA inhibited these advanced fusion phenotypes and allowed us to identify an early stage of fusion at physiological temperature. Although lipid flow between membranes was restricted, the contacting membrane monolayers were apparently transiently connected, as detected by the transformation of this fusion intermediate into complete fusion after treatments known to destabilize hemifusion diaphragms. These reversible connections disappeared within 10-20 min after application of low pH, indicating that after the energy released by HA refolding dissipated, the final low pH conformation of HA did not support membrane merger. Although the dynamic character and the lack of lipid. mixing at 37 degrees C distinguish the newly identified fusion intermediate from the intermediate arrested at 4 degrees C described previously, both intermediates apparently belong to the same family of restricted hemifusion (RH) structures. Because the formation of transient RH structures at physiological temperatures was as fast as fusion pore opening and required less HA, we hypothesize that fusion starts with the formation of multiple RH sites, only a few of which then evolve to become expanding fusion pores.