SOLUTION STRUCTURE OF A HUMAN AMINOACYL-TRNA SYNTHETASE

该子项目是利用 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来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 酪氨酰-tRNA合成酶（TyrRS）是人类氨酰-tRNA合成酶之一，催化蛋白质生物合成的第一步，并参与细胞信号传导活动，如细胞迁移和血管生成。我们已经单独解决了分离的N-末端和C-末端结构域的晶体结构，最近在SSRL对野生型酶以及Y341 A突变体进行了溶液X-射线散射实验，以获得全长酶的溶液结构。野生型全长蛋白在细胞信号传导中是无活性的，而Y341 A突变体具有活性细胞因子活性，这意味着与野生型酶相比，Y341可能具有开放结构。我们通过Guinier图分别获得了野生型和突变型酶的回转半径47和50 <$。电子对距离分布函数有两个mixima，一个在30左右，另一个在60左右。在突变体的情况下，第一个峰显著较低，并且这伴随着在较大间距中分布的增加，导致最大尺寸（Dmax）从150增加到约160。这些结果证实了突变体具有更开放的结构，有力地支持了我们的假设，即N-和C-末端结构域之间的结构域闭合在细胞因子活性的调节中起着关键作用。我们正在建立一个低分辨率的结构信封的基础上的解决方案散射数据的过程中，努力适应到信封的晶畴结构。

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. Tyrosyl-tRNA synthetase (TyrRS) is one of the human aminoacyl-tRNA synthetases that catalyze the first step of protein biosynthesis and are involved in cell-signaling activities such as cell migration and angiogenesis. We have solved the crystal structure of the isolated N-terminal and C-terminal domains individually, and have recently conducted solution x-ray scattering experiments at SSRL on the wild type enzyme as well as Y341A mutant to obtain the solution structure of the full-length enzyme. The wild type full length protein is inactive in cell signaling while Y341A mutant has active cytokine activity, implying the Y341 may have an open structure, compared to that of the wild type enzyme. We obtained the radii of gyration 47 and 50 ¿ for the wild type and mutant enzyme, respectively by Guinier plots. The electron pair distance distribution function has two mixima, one around 30 ¿ and the other around 60 ¿. The first peak is substantially lower in the case of the mutant, and this is accompanied by the increase in the distribution in a larger inter-distances, resulting in the increase in the maximum dimension (Dmax) from 150 ¿ to approximately 160 ¿. These results confirm that the mutant has a more open structure, strongly supporting our hypothesis that the domain closure between N- and C-terminal domains plays a key role in the regulation of the cytokine activity. We are in the process of building a low-resolution structural envelope based on the solution scattering data in an effort to fit the crystal domain structures into the envelope.