Structural and functional study of translational release factor from the viewpoint of molecular mimicry and prion transmission

最近的分子和结构研究，包括来自这个实验室的研究，揭示了被称为翻译因子的蛋白质模仿tRNA的形状。其中一种是多肽释放因子，它编码一种三肽，作为“反密码子”来破译mRNA中的停止密码子。这些发现让我们提出了蛋白质和RNA之间大分子模仿的新概念。此外，出芽酵母的[PSI^+]元件代表翻译释放因子eRF3在细胞质中繁殖和传递的朊病毒构象。在许多层面上，酵母朊病毒类似于哺乳动物朊病毒，人们的兴趣在于了解朊病毒如何能够在等基因菌株中产生变异。我们从分子模拟和朊病毒传播的角度对翻译释放因子进行了研究，发现了以下几个方面。1)变异码生物的eRF1中存在万能解码潜能，并受氨基酸序列的相互作用调节。1.2)翻译释放因子的局部电荷交换改变使义和非同源终止密码子上的多肽释放。3)EF-G通过在核糖体tRNA-mimicry结构域与核糖体再循环因子RRF相互作用参与核糖体拆卸。4)酵母[PSI^+]朊病毒通过准朊病毒状态跨物种传播和易感。5)普遍保守的23S rRNA的A2602在翻译终止时新生肽释放中的关键作用。6)真核生物ⅱ类释放因子eRF3的晶体结构与功能分析。7)酵母eRF3的部分朊病毒结构域掩盖了eRF1.8中eRF3的结合位点)RRF独立于EF-G的核糖体转位酶活性拆卸终止后的核糖体复合体。9)风球菌RRF在大肠杆菌中的异源表达是显性致死性的，其形成的复合体缺乏核糖体拆卸的功能协调。10)在传播到Sup35朊病毒变体的过程中，弱到强或强到弱[PSI^+]转换中保留了构象记忆。少

Recent molecular and structural studies including those from this laboratory have revealed that proteins called translation factors mimic the shape of tRNA. One of them, a polypeptide release factor, encodes a tripeptide that serves as an ‘anticodon' to decipher stop codons in mRNA. These findings let us to propose the novel concept of macromolecular mimicry between protein and RNA. Moreover, The [PSI^+] element of budding yeast represents the prion conformation of translation release factor eRF3 that is propagated and transmitted in the cytoplasm. On many levels, yeast prions are analogous to mammalian prions and much interest lies in understanding how prions are able to generate variation in isogenic strains. We have investigated translational release factors from the viewpoint of molecular mimicry and prion transmission, and uncovered the following aspects.1)Omnipotent decoding potential resides in eRF1 of variant-code organisms and is modulated by the interactions of amino acid seq … More uences within the domain 1.2)Polypeptide release at sense and noncognate stop codons by localized charge-exchange alterations in translational release factors.3)EF-G participates in ribosome disassembly by interacting with ribosome recycling factor RRF at their tRNA-mimicry domains.4)Yeast [PSI^+] prions that are crosstransmissible and susceptible beyond a species barrier through a quasi-prion state.5)The critical role of the universally conserved A2602 of 23S rRNA in the release of the nascent peptide during translation termination.6)Crystal structure and functional analysis of the eukaryotic class II release factor eRF3 from S.Pombe.7)Part of the prion domain of yeast eRF3 masks the eRF3-binding site in eRF1.8)RRF disassembles the posttermination ribosomal complex independent of the ribosomal translocase activity of EF-G.9)Heterologous expression of A.aeolicus RRF in E.coli is dominant lethal by forming a complex that lacks functional coordination for ribosome disassembly.10)Conformational memory preserved in a weak-to-strong or strong-to-weak [PSI^+] conversion during transmission to Sup35 prion variants. Less