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Functional Structure of the GTPase Domain within 28S Ribosomal RNA (Analysis of a Conformational Epitope on RNA Recognized by a Unique Autoantibody)

28S 核糖体 RNA 内 GTP 酶结构域的功能结构（独特自身抗体识别的 RNA 构象表位分析）

基本信息

批准号：
04670140
负责人：
UCHIUMI Toshio
金额：
$ 1.41万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

Ribosomal RNA (rRNA) is highly conserved macromolecule. Currnet evidence shows a functional role of rRNA in protein biosynthesis. However, almost nothing is known about the detailed functional structure of the rRNA and mechanism of its action in the process of protein synthesis. In 1991, we found a site-specific anti-rRNA autoantibody (anti-28S) in sera from patients with autoimmune disease. Anti-28S strongly inhibits protein synthesis at the step of interaction between elongation factors and ribosomes. In this project during three years, 1992 to 1994, we have studied on the structure and function of the antibody-binding region of rRNA using anti-28as a probe. We have reported following findings and clarified involvement of the RNA domain in interaction with elongation factors and the associated GTP hydrolysis :(1) Anti-28S specifically protects a region termed the "GTPase domain" within 28S rRNA from RNase digestion and chemical modifications. Four bases including G-1959 were identified as elements involved in formation of the autoimmune epitope.(2) Ribosomal proteins P1, P2, P0, and L12 bind to be GPTase domain and affect the tertiary structure of the RNA domain.(3) Prokaryotic ribosomes shows very low accessibility to anti-28S.However, a base substitution of A-1067 to G at the position equivalent to eukaryotic 1959 site causes high anti-28S accessibility of the ribosomes, indicating G-1959 is important for ansi-28S recognition.(4) G-1959 is also protected by elongation factor EF-2 from chmical modification with dimethy1 sulfate, suggesting that anti-28S directly blocks the EF-2 action to the GTPase domain.(5) Anti-28S activity is detected in sera from 17 % patients with SLE.All the anti-28S sera also contain anti-P antibody reactive with tha domain-associating proteins P1, P2, and P0.

核糖体RNA（rRNA）是一种高度保守的大分子。目前的证据表明rRNA在蛋白质生物合成中的功能作用。然而，关于rRNA的详细功能结构及其在蛋白质合成过程中的作用机制几乎一无所知。1991年，我们在自身免疫性疾病患者的血清中发现了一种位点特异性的抗rRNA自身抗体（抗28 S）。抗28 S抗体在延伸因子与核糖体相互作用的步骤中强烈抑制蛋白质合成。本课题在1992 ~ 1994年三年中，以抗28为探针，对rRNA抗体结合区的结构和功能进行了研究。我们已经报道了以下发现，并阐明了RNA结构域与延伸因子和相关GTP水解的相互作用：（1）抗28 S特异性保护28 S rRNA内称为“GTP结构域”的区域免受RNA酶消化和化学修饰。包括G-1959在内的4个碱基被鉴定为参与自身免疫表位形成的元件。(2)核糖体蛋白P1、P2、P0和L12与GTP酶结构域结合并影响RNA结构域的三级结构。(3)在真核生物中，G-1959对抗-28S识别起重要作用，而在真核生物中，G-1959对抗-28S识别起重要作用。(4)G-1959也受到延伸因子EF-2的保护，不受硫酸二甲酯的化学修饰，这表明抗28 S抗体直接阻断EF-2对GT3结构域的作用。(5)17%的SLE患者血清中检测到抗28 S抗体，所有抗28 S血清均含有与结构域相关蛋白P1、P2和P0反应的抗P抗体。