新型海洋真菌天然产物Viridicatumtoxins抑制万古霉素耐药肠球菌作用机制研究

万古霉素耐药肠球菌的出现对开发新型抗感染药物提出了迫切要求，寻求和开发海洋微生物资源，将为抗感染新药发现提供新的思路。我们前期从一株海洋真菌的发酵产物中分离鉴定了一系列含四环素骨架的viridicatumtoxin类化合物。其中viridicatumtoxin B对万古霉素耐药肠球菌有极强的抑制能力。酶活实验推测其潜在作用靶点是细胞壁合成中的UPP合成酶，而并非四环素类抗生素的靶点核糖体。本项目中我们将评价这类化合物与UPP合成酶的相互作用能力，确证UPP合成酶是潜在的作用靶点；解析UPP合成酶及其与viridicatumtoxin B的复合物晶体结构；基于晶体结构，改造、开发抑菌能力更强、安全性更高的viridicatumtoxin类先导衍生化合物。预期结果不仅将揭示viridicatumtoxin B高效抑制UPP合成酶的分子机制，也将为改造现有四环素类抗生素的结构与功能提供有力依据。

The emergence of vancomycin-resistant Enterococcus faecalis (VREF) has put forward an urgent demand for the development of new anti-infective drugs. Seeking and exploiting marine microbial resources provides a new way for the discovery of new drugs to treat the infections caused by VREF.. Viridicatumtoxins, a series of structural analogs of tetracycline antibiotics, were isolated and identified from marine fungus Paecilomyces sp. CMB-MF010 in our research group. One of them, viridicatumtoxin B, has a very strong inhibitory effect on VREF. Previous studies proposed the potential biological target of viridicatumtoxin B is UPP synthase, but not the ribosome targeted by clinically used tetracycline antibiotics.. In this project, we will evaluate the interaction and binding affinity between viridicatumtoxins and UPP synthase using IC50, MIC and SPR related assays, to confirm that UPP synthase is the real drug target of viridicatumtoxins. We also plan to grow and solve the crystal structure of VREF UPP synthase as well as its co-crystal structure with viridicatumtoxin B; and we will modify, develop more viridicatumtoxin derivatives with stronger inhibition activity and higher biosafety based on the co-crystal structures of VREF UPP synthase with viridicatumtoxin B. The expected results of this project will not only reveal the molecular mechanism of UPP synthase activity highly inhibited by viridicatumtoxin B, but also inspire the rational structural modification of tetracycline antibiotics in the future.