MEMBRANE REMODELING DURING VIRAL INDUCED SYNCYTIA FORMATION

由细胞表达的分子机制使膜聚结， 对于流感病毒来说相对简单， (HA)单独用于膜融合是足够的。 关于如何降低 pH诱导的HA重折叠产生膜融合中心， 其中HA融合融合膜的脂质并打开融合孔 来连接它们的含水物。 任何一种HA都可能首先导致 蛋白质离子通道，然后引导脂质合并，或HA可以 首先产生一个局部的双向连接，然后断开， 毛孔 目前尚不清楚这种没有融合的脂质连接是否 孔（半融合），这是可实现的突变体HA，是一个 非生理中间体或融合中的连续步骤 由野生型HA（wt-HA）介导。 为了检测通常寿命短的 中间体，我们降低了活化HA的密度和流动性， 同时测量脂质混合和融合孔电导， 一个同时进行电生理记录和荧光的系统 我们发明的视频显微镜 取得了实质性的改进 今年，控制和分析这些实验的软件。 在这些次优条件下，Wt-HA确实引起半融合。然而，在这方面， 这种半融合是稳定的，而不是融合的中间体。 如果没有 在脂质混合开始之前，孔是开放的， 所有这些都表明，虽然激活的HA介导了局部半融合， 同时限制了这种半融合中间体的膨胀， 阻碍脂质扩散直至融合孔形成。

The molecular machinery expressed by cells to coalesce membranes is relatively simple in the case of influenza virus, where hemagglutinin (HA) alone is sufficient for membrane fusion. The debate on how low pH-induced refolding of HA produces membrane fusion centers on the order in which HA merges the lipids of fusing membranes and opens a fusion pore to connect their aqueous contents. Either HA can first cause a proteinaceous ionic channel which then guides lipids to merge, or HA can first produce a local lipidic connection which then breaks to form a pore. It is unknown whether such a lipid connection without a fusion pore (hemifusion), which is achievable for a mutant HA, is a non-physiological intermediate or a sequential step in the fusion mediated by wild-type HA (wt-HA). To detect normally short-living intermediates, we reduced the density and mobility of activated HA, while simultaneously measuring lipid mixing and fusion pore conductance using a system of simultaneous electrophysiological recording and fluorescence video microscopy that we developed. Substantial improvements were made this year to the software controlling and analysing these experiments. Wt-HA did cause hemifusion under these suboptimal conditions. However, rather than an intermediate to fusion, this hemifusion was stable. If no pores were open prior to onset of lipid mixing, pores would not open at all, suggesting that while activated HA mediates local hemifusion, it simultaneously limits expansion of this hemifusion intermediate and impedes lipid diffusion till fusion pore formation.