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产生功能性反应。这样的反应，这可能是额外的小分子量辅因子的影响，是重要的细菌和真核基因的控制机制的关键组成部分。然而，对调控新生肽和辅因子的分子识别机制以及核糖体应答的基本原理知之甚少。细菌病原体中许多可诱导的抗生素抗性基因的表达是由抗生素促进的新生肽依赖性程序化翻译停滞控制的。最近，一类独特的调节新生肽编码的许多大环内酯类耐药基因的调节顺反子已被确定。这类肽的特征在于存在“RLR”（Arg-Leu-Arg）基序。初步研究表明，这些肽指导的程序化翻译停滞机制主要不同于所有先前研究的系统。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阻滞，从而产生已知最短的停滞肽。这种最小化的失速新生肽和失速辅因子（诱导抗生素）的确切结合位点的知识提供了前所未有的工具，用于解开新生肽和小辅因子控制的程序化翻译停滞的一般机制的重要基本方面。在这三个具体目标的建议，我们将1）探索指导核糖体失速所需的最低限度的新生肽的结构特征，2）分析抗生素辅因子在程序化翻译停滞中的作用，和3）解开停滞信号识别的机制和结构特征的核糖体在逮捕状态。

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.