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

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.

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。

进入21世纪以来，由于传统抗病原菌感染药物被广泛的应用于临床和畜牧业，大量的抗菌药物残留存在于环境中，造成耐药菌在动物—环境—人类中的交互传播，导致了病原菌耐药性在全球范围内的快速上升，病原菌耐药性的快速上升正严重危胁着人类的生存与健康。因此，急需开发新型抗耐药菌感染的药物。由于陆生微生物资源的日益匮乏，寻求和开发海洋、中药等特殊生境来源的新型天然活性化合物，将为抗感染新药发现提供新的思路。. 本研究从一株海洋真菌Paecilomyces sp. CMB-MF010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，发现其中的viridicatumtoxin A（VirA）和viridicatumtoxin B（VirB）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标是细胞壁合成中的UPP合成酶（UPPS），而并非四环素类抗生素的靶标核糖体。我们深入评价了这类化合物与UPP合成酶的相互作用能力，确证了UPP合成酶是其潜在的作用靶标；解析了UPP合成酶及其与viridicatumtoxin B的复合物晶体结构，揭示了viridicatumtoxin B高效抑制UPP合成酶的分子机制，为改造现有四环素类抗生素的结构与功能提供了有力依据。