Hygromycin A: Activity, Biosynthesis, Export, Resistance and Regulation

描述（由申请人提供）：许多临床上重要的抗生素，包括大环内酯类（阿奇霉素、特利红霉素）、四环素类、氨基糖苷类（庆大霉素）和最近的恶唑烷酮类（利奈唑胺）靶向细菌核糖体，这是细胞内蛋白质合成所必需的。使用这些和其他抗生素对抗病原微生物不可避免地导致细菌耐药性的发展，这是临床环境中日益严重的问题。因此，继续需要开发对多重耐药细菌有效的新抗生素，以及能够延缓对这些细菌产生不可避免的耐药性的方法。核糖体是开发新抗生素最丰富和最有效的靶标之一。这种药物开发工作可以建立在分子水平上对核糖体与化学不同结构的相互作用的理解，生物活性其他方面的结构要求（包括细胞摄取）以及耐药性发展的可能机制。湿霉素A （HygA）是一种从吸湿链霉菌中分离出来的抗生素，对革兰氏阳性和革兰氏阴性细菌都有活性，其作用机制涉及与核糖体的独特但神秘的结合。HygA的化学结构也与其他靶向核糖体的抗生素有很大不同。由于这些原因，HygA有可能发展成为一类新的临床有用的抗生素。该项目的长期目标是全面了解潮霉素a （HygA）的活性、生物合成、出口、耐药性和调控（ABERR）。本项目期间有5个具体目标，将采用多学科合作的方法与遗传、生化和结构研究。目的1。详细了解HygA生物合成过程中关键和新步骤的酶学。目标2。阐明生物合成途径的中间体和分流产物HygA如何与核糖体结合。目标3。确定最终产物HygA从细胞中排泄的机制。目标4。评估抗生素和吸湿葡萄球菌核糖体共价修饰在赋予HygA和相关生物合成产物抗性中的相对作用。目标5。确定HygA ABERR过程是如何调节的，以及它们在多大程度上是协调的。

DESCRIPTION (provided by applicant): Many clinically important classes of antibiotics, including macrolides (azithromycin, telithromycin), tetracyclines, aminoglycosides (gentamycin), and more recently oxazolidinones (linezolid) target the bacterial ribosome, which is essential for intracellular protein synthesis. Use of these and other antibiotics against pathogenic microorganisms inevitably leads to development of bacterial resistance, an increasing problem within the clinical setting. There is thus a continued need to develop new antibiotics, effective against multi-drug resistant bacteria, and for approaches which can retard the inevitable development of resistance to these. The ribosome represents one of the richest and most effective targets for development of new antibiotics. Such drug development efforts can build upon a molecular level understanding of the ribosomal interactions with chemically distinct architectures, structural requirements for other aspects of biologically activity (including cellular uptake) and likely mechanisms for development of resistance. Hygromycin A (HygA), an antibiotic isolated from Streptomyces hygroscopicus and is active against both Gram-positive and Gram-negative bacteria and a mechanism of action which involves a distinct but enigmatic binding to the ribosome. HygA also has a chemical architecture which differs significantly from other antibiotics which target the ribosome. For these reasons HygA is of interest for potential development into new class of clinically-useful antibiotics. The long term project objective is to build a comprehensive understanding of hygromycin A (HygA) activity, biosynthesis, export, resistance and regulation (ABERR). This project period has 5 specific aims which will be pursed using a multi-interdisciplinary and collaborative approach with genetic, biochemical and structural studies. Aim 1. Obtain a detailed understanding of the enzymology of key and novel steps in the HygA biosynthetic process. Aim 2. Elucidate how HygA, biosynthetic pathway intermediates and shunt products, bind to ribosomes. Aim 3. Determine mechanisms by which the final product HygA is excreted from the cell. Aim 4. Evaluate the relative roles of covalent modification of both the antibiotic and the S. hygroscopicus ribosome in conferring resistance to HygA and related biosynthetic products. Aim 5. Determine how HygA ABERR processes are regulated, and to what extent are they coordinated. PUBLIC HEALTH RELEVANCE: There is continued need for new antibiotics effective against multi-drug resistant bacteria, and for approaches which can retard the inevitable development of resistance to these. Actinomycetes are soil bacteria and serve both as a source for the majority of antibiotics used clinically to treat bacterial infections and a repository for resistance mechanisms to these. This study will evaluate biological activity and resistance mechanisms associated with the natural product hygromycin A and related compounds and may ultimately lead to new therapies for treatment of bacterial infections.