RNA modification and antibiotic resistance

抗生素在细菌感染治疗中的应用彻底改变了现代医学实践。在此后的几十年里，不适当的控制使用和细菌种群对这些药物产生耐药性的显着能力的结合严重限制了许多抗生素的临床用途。我们现在正处于一个关键时刻，大多数有用的抗生素都具有已知的，有时是广泛的耐药性，很少有新的替代品或对抗耐药性问题的战略正在积极开发中。许多临床上有用的抗生素靶向细菌核糖体。对这些药物的一种日益普遍的耐药形式是通过获得性或内在甲基转移酶改变核糖体RNA（rRNA）的修饰状态。虽然负责整合这些抗生素耐药性相关rRNA修饰的酶是已知的，但我们对它们的作用机制（如特异性底物识别）了解得少得多，这可能提供可行的新靶点来对抗耐药性。此外，我们目前对rRNA甲基化如何影响核糖体-抗生素相互作用的分子基础也缺乏了解。本申请中提出的实验将直接解决我们对rRNA甲基化和细菌抗生素耐药性的基础知识中的这些关键空白。在前两个目标中，我们将定义两种不同的rRNA修饰酶，获得性氨基糖苷类耐药16 S rRNA（m7 G1405）甲基转移酶（Aim 1）和固有的结核分枝杆菌甲基转移酶TlyA（Aim 2）的核糖体亚基识别的分子机制。接下来，我们将开发一个新的计算和实验框架，以了解甲基化rRNA相互作用（目标3）。我们的目标是在分子水平上解释rRNA修饰如何限制药物疗效以及如何避免这些影响。总的来说，这三个独立但互补的目标的结果将加深我们对rRNA修饰酶所使用的分子策略以及rRNA甲基化对细菌抗生素耐药性的影响的基本理解。我们的研究结果将支持未来的创新策略，以对抗这些酶所赋予的耐药性，例如，通过促进m7 G1405甲基转移酶活性或30 S底物结合抑制剂的开发，也可能导致能够完全避免rRNA修饰影响的新型抗菌剂的合理设计。

The application of antibiotics to the treatment of bacterial infections revolutionized modern medical practice. In the decades since, a combination of improperly controlled usage and the remarkable ability of bacterial populations to develop resistance to these drugs has severely restricted the clinical usefulness of many antibiotics. We are now at a critical juncture where the majority of useful antibiotics have known and sometimes extensive resistance, and few novel replacements or strategies to combat the resistance problem are in active development. Many clinically useful antibiotics target the bacterial ribosome. One increasingly prevalent form of resistance to these drugs is alteration of the modification status of the ribosomal RNA (rRNA) via acquired or intrinsic methyltransferase enzymes. While enzymes responsible for incorporating these antibiotic resistance- associated rRNA modifications are known, we understand far less about their mechanisms of action (such as specific substrate recognition), which might offer viable new targets to counter the resistance. Further, we also currently have a poor understanding of the molecular basis for how rRNA methylation affects ribosome-antibiotic interactions. The experiments proposed in this application will directly address these critical gaps in our fundamental knowledge of rRNA methylation and bacterial antibiotic resistance. In the first two aims we will define the molecular mechanisms of ribosome subunit recognition by two different rRNA modification enzymes, the acquired aminoglycoside-resistance 16S rRNA (m7G1405) methyltransferases (Aim 1) and the intrinsic Mycobacterium tuberculosis methyltransferase TlyA (Aim 2). Next, we will develop a new computational and experimental framework for understanding antibiotic-methylated rRNA interactions (Aim 3). Our goal is to explain at the molecular level how rRNA modifications limit drug efficacy and how these effects can be evaded. Collectively, the results of these three independent but complementary aims will deepen our fundamental understanding of the molecular strategies used by rRNA modification enzymes and the impacts of rRNA methylation on antibiotic resistance in bacteria. Our results will support future innovative strategies to counter the resistance conferred by these enzymes, for example, by facilitating the development of inhibitors of m7G1405 methyltransferase activity or 30S substrate binding, and could also lead to the rational design of novel antimicrobials capable of fully evading the effects of rRNA modification.