Neutron diffraction experiment with the Y116S variant of transthyretin using iBIX at J-PARC: application of a new integration method
Neutron diffraction experiment with the Y116S variant of transthyretin using iBIX at J-PARC: application of a new integration method
复制标题
J-PARC 使用 iBIX 进行运甲状腺素蛋白 Y116S 变体的中子衍射实验：新积分方法的应用
DOI：
10.1107/s2059798320012498
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Mizuguchi Mineyuki
中科院分区：
文献类型：
--
作者：
Kusaka Katsuhiro;Yokoyama Takeshi;Yamada Taro;Yano Naomine;Tanaka Ichiro;Mizuguchi Mineyuki
转甲状腺素(Transhyretin，TTR)是30多种淀粉样蛋白中的一种，在患有AtR淀粉样变性的患者中发现的淀粉样纤维就是由这种蛋白组成的。在老年性系统性淀粉样变性(SSA)中，野生型TTR淀粉样蛋白在心脏中积聚。ATTR淀粉样变性发生在比SSA年轻得多的年龄，并且受影响的个体携带TTR突变。自然产生的Y116S淀粉样变异体比野生型TTR形成更多的淀粉样原纤维。因此，Y116S突变降低了TTR结构的稳定性。对Y116S TTR进行了中子衍射实验，通过结构比较，阐明了Y116S变异体和野生型TTR结构稳定性变化的机理。在优化的晶化条件下生长了Y116S的大晶体，最终获得了2.4 mm~3的单晶。这种晶体在日本东海的日本质子加速器研究综合体(J-PARC)使用茨城生物晶体衍射仪(IBIX)进行了飞行时间(TOF)中子衍射。在加速器运行功率为500 kW的情况下，在14天内获得了完整的中子结构分析数据集。提出了一种新的积分方法，改进了数据统计，并将新方法应用于Y116S变种的TOF衍射数据的简化。完成了数据整理，获得了1.9 á分辨率下布拉格反射的积分强度，用于结构优化。此外，还获得了1.4 ？分辨率的X射线衍射数据，用于中子-X射线联合精修。
Transthyretin (TTR) is one of more than 30 amyloidogenic proteins, and the amyloid fibrils found in patients afflicted with ATTR amyloidosis are composed of this protein. Wild-type TTR amyloids accumulate in the heart in senile systemic amyloidosis (SSA). ATTR amyloidosis occurs at a much younger age than SSA, and the affected individuals carry a TTR mutant. The naturally occurring amyloidogenic Y116S TTR variant forms more amyloid fibrils than wild-type TTR. Thus, the Y116S mutation reduces the stability of the TTR structure. A neutron diffraction experiment on Y116S TTR was performed to elucidate the mechanism of the changes in structural stability between Y116S variant and wild-type TTR through structural comparison. Large crystals of the Y116S variant were grown under optimal crystallization conditions, and a single 2.4 mm3 crystal was ultimately obtained. This crystal was subjected to time-of-flight (TOF) neutron diffraction using the IBARAKI biological crystal diffractometer (iBIX) at the Japan Proton Accelerator Research Complex, Tokai, Japan (J-PARC). A full data set for neutron structure analysis was obtained in 14 days at an operational accelerator power of 500 kW. A new integration method was developed and showed improved data statistics; the new method was applied to the reduction of the TOF diffraction data from the Y116S variant. Data reduction was completed and the integrated intensities of the Bragg reflections were obtained at 1.9 Å resolution for structure refinement. Moreover, X-ray diffraction data at 1.4 Å resolution were obtained for joint neutron–X-ray refinement.