MATURATION INTERMEDIATES OF A T=4 VIRUS CAPSID STUDIED BY TIME-RESOLVED X-RAY SC

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。 新月形虫Omega病毒样颗粒是一种T=4病毒衣壳，经历了一个pH促进的成熟过程。使用SSRL BL4-2上改进的仪器，我们已经开始研究与成熟过程相关的结构变化的动力学。在这一努力之前，我们检测到一种结构中间体[Canady等人。J·摩尔比奥尔。311,803-814(2001)]，但当时可达到的数据质量不允许我们分析结构细节。最近的实验表明，由于仪器的极大改进，特别是探测器灵敏度的提高和更大的2D活动面积以及更高的束流水平，更少的病毒样颗粒(VLP)足以获得更高质量的数据。通过进行手动混合，然后进行一系列时间分辨数据采集(每次3秒曝光)，我们已经能够在中性(pH 7.6)和pH 5.0之间分离出一种结构中间体，这在我们早期的研究中被用来促进成熟。另一个重要的观察结果是，两个RNA含量不同的VLP呈现出略有不同的形状和直径。这是第一次直接实验观察到RNA支架在病毒形态中的重要作用。

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. Nudaurelia capensis omega virus-like particle, a T=4 virus capsid, undergoes a pH promoted maturation process. Using the much improved instrumentation on SSRL BL4-2 we have begun studying the kinetics of structural change associated with the maturation process. Prior to this effort, we detected a structural intermediate [Canady et al. J .Mol. Biol. 311, 803-814 (2001)], but the data quality achievable then did not permit us to analyze structural details. Very recent experiments demonstrate that a much smaller quantity of virus-like particle (VLP) is sufficient to obtain higher quality data due to the vastly improved instrumentation, in particular the improved detector sensitivity and larger 2D active area as well as the higher beam flux level. Performing manual mixing, followed by a series of time-resolved data acquisition (each 3 sec exposure), we have been able to isolate a structural intermediate at intermediary pH values between neutral (pH 7.6) and pH 5.0, which was used to promote the maturation in our earlier studies. The other important observation is that two VLPs with different RNA contents show slight different shape and diameter. This is the first direct experimental observation of the significant role of RNA scaffolding in virus morphology.