猪源粪肠球菌耐药基因optrA作用机制研究

Enterococcus bacteria, important opportunistic pathogens in human and animal intestinal, are becoming a difficult problem in the prevention and treatment of infectious diseases due to their intrinsic and acquired drug resistance. A novel drug resistant gene optrA, which mediates resistance to oxazolidinones and phenicols, was reported in Enterococcus faecalis from swine in 2015 and brought great threat to the healthy development of the swine industry and public health. Previous research suggested that gene optrA codes an ATP-binding cassette transporter protein, but the mechanism of gene optrA mediating drug resistance is not fully understood. This proposal intends to develop the optrA-positive recombinant strain, determine the levels of oxazolidinones and phenicols in bacteria to confirm the role of ATP-binding cassette transporter protein, and investigate the molecular regulatory networks of proteins and pathways related to optrA by means of proteomics and metabolomics. OptrA-positive strains of swine Enterococcus faecalis from clinical isolates will be used to validate the regulatory networks. The aim of this proposal is to elucidate the mechanism of gene optrA in Enterococcus faecalis of swine origin, which will provide scientific basis for the clinical rational use of drugs and the development of new drugs for veterinary medicine.

肠球菌属细菌是人及畜禽肠道中重要的条件性致病菌，由于其固有耐药和获得性耐药日益严重，逐渐成为感染性疾病防治面临的困难问题。2015年，猪源肠球菌中发现了可同时介导恶唑烷酮类和酰胺醇类药物耐药的新型耐药基因optrA，给养猪业的健康发展和公共卫生带来了极大威胁。已有研究初步推断optrA基因编码腺苷三磷酸结合盒转运蛋白，但是optrA基因介导耐药性产生的作用机制尚不完全清楚。针对此问题，本项目拟构建optrA基因阳性工程菌株，通过定量分析菌体内恶唑烷酮类和酰胺醇类药物含量验证腺苷三磷酸结合盒转运蛋白的作用，并运用蛋白质组学和代谢组学技术研究optrA基因相关的蛋白质组和代谢通路变化所构成的分子调控网络，最后以临床分离的猪源粪肠球菌验证optrA基因的调控网络。本项目旨在阐明猪源粪肠球菌中optrA基因的作用机制，为兽医临床合理用药和新药研制提供科学依据。

猪源肠球菌中发现的新型耐药基因optrA可同时介导恶唑烷酮类和酰胺醇类药物耐药，给养猪业的健康发展和公共卫生带来了极大威胁。optrA蛋白属于ABC转运蛋白，但是却缺少主要的跨膜区域，optrA基因介导耐药性产生的作用机制尚不完全清楚。针对此问题，本项目构建了optrA基因阳性工程菌株，通过定量分析菌体内恶唑烷酮类和酰胺醇类药物含量证明optrA基因应该是以核糖体保护而非转运蛋白方式导致耐药。本项目进一步运用蛋白质组学和代谢组学技术研究optrA基因相关的蛋白质组和代谢通路变化所构成的分子调控网络，结果表明30S核糖体S6蛋白、乌头酸水合酶B和RNA-结合蛋白Hfq等蛋白以及NADP、ADP、二磷酸尿苷、精氨酸、谷氨酸、棕榈酸、单磷酸腺苷和二磷酸鸟苷等代谢物为optrA基因介导耐药的关键节点。本项目的研究结果为深入阐明猪源粪肠球菌中optrA基因的作用机制和新药研制提供科学依据。