SOLUTION SCATTERING STUDY ON PRO-FUSION INTERMEDIATE OF INFLUENZA HEMAGGLUTININ

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 我们研究了菠萝蛋白酶释放流感血凝素的pH依赖性构象转换的小角溶液X射线散射。流感病毒的三聚体血凝素（HA）糖蛋白负责宿主细胞粘附和膜融合。已知内吞作用中的酸性环境触发大规模构象转换。X射线晶体学给出了初始和后融合状态的三维结构。迄今为止，几乎没有关于激活的中间状态的结构信息，这是由于它们的短暂性质对其宿主附着和融合功能至关重要。 我们通过降低溶液pH值触发构象转换，并通过溶液X射线散射监测HA构象随时间的演变。 我们在BioCAT获得了令人鼓舞的结果，与我们在2007年夏天在SSRL获得的结果非常相似。BioCAT的数据质量明显提高。我们观察到的X射线散射曲线在中间散射角处的特征与2007年观察到的略有不同，表明样品制备过程中存在轻微变化。我们正在评估样品制备方案，并计划在不久的将来进行更多的实验。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We study the pH dependent conformational switching of bromelain-released influenza hemagglutinin by small angle solution x-ray scattering. The trimeric hemagglutinin (HA) glycoprotein is responsible for both host cell attachment and membrane fusion in influenze virus. The acidic environment in endocytosis is known to trigger a large scale conformational switching. X-ray crystallography has given the three dimensional structures of the initial and the post fusion states. There is little structural information available so far for activated intermediate states due to their transient nature central to their host attachment and fusion functions. We trigger the conformational switching by lowering solution pH and monitor the evolution of HA conformation via solution x-ray scattering as a function of time over several minutes. We obtained encouraging results at BioCAT fairly similar to what we had obtained at SSRL in summer 2007. The improved data quality was evident at BioCAT. We observed x-ray scattering curves which has slightly different features at intermediary scattering angles than had been observed in 2007, indicating the slight variation in sample preparation. We are evaluating sample preparation protocol and planning on conducting additional experiments in near future.