Programmed translation arrest controlled by nascent peptides and antibiotics

描述（由申请人提供）： 摘要 核糖体可以对特定的新生肽做出功能性反应。这种反应还受到小分子量辅助因子的影响，是重要细菌和真核基因控制机制的关键组成部分。然而，人们对调节性新生肽和辅因子的识别分子机制以及核糖体反应的基本原理知之甚少。细菌病原体中许多诱导型抗生素抗性基因的表达受到抗生素促进的新生肽依赖性程序性翻译停滞的控制。最近，已鉴定出在许多大环内酯类抗性基因的调节顺反子中编码的一类独特的调节新生肽。此类肽的特征在于存在“RLR”（精氨酸-亮氨酸-精氨酸）基序。初步研究表明，这些肽引导的程序化翻译停滞的机制与之前研究的所有系统基本上不同。此外，发现短至三个或四个氨基酸的新生肽足以指导药物依赖性核糖体停滞，从而产生已知的最短的停滞肽。这种简约的停滞新生肽和对停滞辅因子（诱导抗生素）精确结合位点的了解为阐明新生肽和小辅因子控制的程序性翻译停滞的一般机制的重要基本方面提供了前所未有的工具。在该提案的三个具体目标中，我们将1）探索指导核糖体停滞所需的最小新生肽的结构特征，2）分析抗生素辅助因子在程序性翻译停滞中的作用，以及3）揭示停滞状态下核糖体停滞信号识别的机制和结构特征。

DESCRIPTION (provided by applicant): ABSTRACT The ribosome can functionally respond to specific nascent peptides. Such response, which can be additionally affected by small molecular weight cofactors, is a key component of the mechanism of control of important bacterial and eukaryotic genes. However, the molecular mechanisms of recognition of the regulatory nascent peptide and cofactor and the basic principles of the ribosomal response are poorly understood. Expression of a number of inducible antibiotic resistance genes in bacterial pathogens is controlled by nascent peptide-dependent programmed translation arrest promoted by antibiotic. Recently, a distinct class of regulatory nascent peptides encoded in the regulatory cistrons of many macrolide resistance genes has been identified. The peptides of this class are characterize dby the presence of an 'RLR' (Arg-Leu-Arg) motif. Preliminary studies showed that the mechanism of programmed translation arrest directed by these peptides is principally different from all of the previously studied systems. Furthermore, nascent peptides as short as three or four amino acids were found to be sufficient to direct drug-dependent ribosome arrest thereby yielding the shortest known stalling peptides. Such minimalistic stalling nascent peptides and the knowledge of the exact binding site of the stalling cofactor (the inducing antibiotic) provide unprecedented tools for unraveling important fundamental aspects of the general mechanisms of nascent peptide- and small cofactor-controlled programmed translation arrest. In the three specific aims of this proposal we will 1) explore the structural features of the minimalist nascent peptide required for directing ribosome stalling, 2) analyze the role of the antibiotic cofactor in programmed translation arrest, and 3) unravel the mechanism of the stalling signal recognition and structural features of the ribosome in the arrested state.