瑞士乳杆菌素NX371广谱抗菌的分子机制研究

瑞士乳杆菌素（Helveticin）是一类具抗菌活性的蛋白质类细菌素。针对大部分乳酸菌细菌素仅仅对革兰氏阳性菌有抗菌作用和化学防腐剂潜在的食品安全风险等问题，在分离得到一株广谱抗菌活性的嗜酸乳杆菌NX2-6和完成基因组测序的基础上，通过生物信息学结合蛋白质谱鉴定，得到具有广谱抗菌活性的抗菌蛋白瑞士乳杆菌素NX371。项目通过同源建模技术预测瑞士乳杆菌素的空间结构、活性中心和作用位点; LC-MS/MS和核磁共振解析NX371水解肽聚糖的位点; 等热滴定量热和表面等离子共振等分析其与革兰氏阳性和阴性菌细胞壁和膜的相互作用；并通过分子改造和定点突变的手段，验证其抑菌活力，阐明瑞士乳杆菌素广谱抗菌活力的结构基础和分子作用理论模型，揭示瑞士乳杆菌素NX371对革兰氏阳性菌和阴性菌的抗菌作用的分子机制。研究结果可为设计高效的广谱抗菌蛋白和开发新型的生物源食品防腐剂提供理论依据和技术参数。

Helveticin is a class of antibacterial proteins. This project is aimed at problems that most bacteriocins produced from lactic acid bacteria have only antibacterial effects against Gram-positive bacteria and the potential food safety risks of chemical preservatives. We mined a new helveticin NX371 with broad-spectrum antimicrobial activity by bioinformatics based on the complete genome sequencing of Lactobacillus acidophilus NX2-6. In the study, the spatial structure, active center and action site of NX371 will be predicted by homology modeling, the site of NX371 hydrolyzed substrates and site will be resolved by LC-MS / MS and nuclear magnetic resonance. The interaction between NX371 and both cell walls and membranes of Gram-positive and Gram-negative bacteria will be measured by Isothermal Titration Calorimetry (ITC) and Surface Plasmon Resonance (SPR), and the antibacterial activity and effect will be verified through the site-directed mutation. Finally, the molecular structure and action model of NX371 with broad-spectrum antimicrobial activity will be clarified; and the research results will provide both the theory for designing more efficient broad-spectrum antibacterial proteins and technical parameters for the manufacture of new bio-source food preservatives.