SOLUTION SCATTERING STUDY ON PRO-FUSION INTERMEDIATE OF INFLUENZA HEMAGGLUTININ

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 我们用小角溶液X射线散射研究菠萝酶释放的流感血凝素的pH依赖性构象转换。流感病毒的三聚体血凝素(HA)糖蛋白负责宿主细胞的附着和膜融合。众所周知，内吞作用中的酸性环境会触发大规模的构象转换。X射线结晶学给出了聚变初期和聚变后的三维结构。到目前为止，对于激活的中间状态，由于其对宿主附着和融合功能至关重要的瞬变性质，目前几乎没有可用的结构信息。我们通过降低溶液pH来触发构象转换，并通过几分钟的溶液X射线散射来监测HA构象的演变。我们在BioCAT上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。在BioCAT，数据质量的改善是显而易见的。我们观察到了X射线散射曲线，其中间散射角的特征与2007年观察到的略有不同，表明样品制备过程中略有变化。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.