SOLUTION STRUCTURE OF A HUMAN AMINOACYL-TRNA SYNTHETASE

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。 酪氨酰-tRNA合成酶(Tyrosyl-tRNA synthetase，TyrRS)是一种催化蛋白质生物合成第一步的人类氨基酰-tRNA合成酶，参与细胞迁移和血管生成等细胞信号活动。我们已经分别解决了分离的N-末端和C-末端结构域的晶体结构，并于最近在SSRL对野生型酶和Y341A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转导中没有活性，而Y341a突变体具有活跃的细胞因子活性，这意味着Y341与野生型酶相比可能具有开放的结构。用Guinier图分别得到野生型和突变型酶的旋转半径分别为47和50°。电子对距离分布函数有两个极大值，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，这伴随着较大距离内分布的增加，导致最大尺寸(Dmax)从150？增加到大约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-末端和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关键作用。我们正在根据溶液散射数据建立一个低分辨率的结构包络，以努力将晶域结构拟合到包络中。

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.