异戊酰螺旋霉素Ⅰ抗感染新靶点及其作用机制的研究

可利霉素2019年批准为国家一类新药，它是利用生物技术研制的新型大环内酯类抗生素(MA)，异戊酰螺旋霉素Ⅰ（ISPⅠ）是可利霉素的主组分之一。MA通常作用于细菌核糖体50S亚基，阻碍细菌蛋白质合成，起到抑菌作用。ISPⅠ在低浓度时对芽孢杆菌、链球菌等革兰氏阳性菌具有杀菌作用，而且对结核分枝杆菌的抑制活性明显优于螺旋霉素等MA。这提示ISPⅠ除了抑制核糖体之外还可能结合新的抗菌作用靶点。本项目以小肠芽孢杆菌、肺炎链球菌、金黄色葡萄球菌、藤黄微球菌为研究对象，分析出这些敏感菌中加入ISPⅠ后导致的组学变化，利用加入报告基团的ISPⅠ探针鉴定出抗菌作用的新靶点；并通过活性检测、免疫沉淀、SPR检测、基因阻断等方法进一步证实ISPⅠ与靶蛋白之间的相互作用；分别解析ISPⅠ与细菌核糖体、关键靶蛋白结合的三维结构，阐明ISPⅠ抗菌活性增强的新机制，为ISPⅠ的化学结构优化与新药研发提供有益指导。

Carrimycin was the first class new drugs approved in 2019. It is an innovative macrolide antibiotic (MA) produced by biotechnology. Isovalerylspiramycin Ⅰ (ISPⅠ) is one of the main components of carrimycin. MA act as antibiotics by binding to bacterial 50S ribosomal subunit and interfering with protein synthesis, and usually play a bacteriostatic role. However, ISPⅠ has a bactericidal effect on many Gram-positive bacteria such as Bacillus and Streptococcus at low concentrations, and its inhibitory activity against Mycobacterium tuberculosis is more potent than that of spiramycin and other MAs. These results indicated that ISPⅠ may bind to new antibacterial targets in addition to inhibiting ribosomes. This project takes Bacillus intestinalis, Streptococcus pneumoniae, Staphylococcus aureus and Micrococcus luteus as the subjects, analyzes the transcriptomics and proteomics changes caused by the addition of ISPⅠ to these sensitive bacteria, and uses the ISPⅠ probe with reporter group to identify the new antibacterial targets of ISPⅠ. The interactions between ISPⅠ and the target proteins were further confirmed by methods such as biological assay, immunoprecipitation, SPR detection and genes blocking. The determination the three-dimensional structure of ISPⅠseparate binding to bacterial ribosome and key target proteins may help to elucidate the new mechanism of enhancing the antibacterial activity of ISPⅠ. These results will provide the valuable information for the chemical structure optimization of ISPⅠand new drug development.