噬菌体尾部蛋白介导噬菌体对宿主菌特异性吸附的机理研究

In recent years, the emergence of multi-drug resistant bacteria poses a severe challenge to antibiotic therapy, phage therapy is considered as an alternative way of controlling bacterial infections and contaminations. Among them, tailed phages accounted for 96% of the total phages. Phage’s host specificity depends largely on the recognition and adsorption of the phage tail to its host surface receptors, causing subsequent process, and ultimately kill the bacteria. Therefore, recognition and analysis of tail structure and tail genes function is the required step for undestanding the host specificity of bacteriophages. In this study, three completely different phages will be studied. Their morphology and molecular genetics features will be fully characterised, the receptors and the tail proteins which are responsible for receptor binding will be identified and validated using genome sequencing, construction of mutant library, protein expression and purification, surface plasmon resonance technology, construction of truncated receptor binding proteins and receptors, site-directed mutagenesis, construction of mutants and complementary strains and so on. Finally, the mechanism of phage-host interaction from the molecular level and the molecular mechanism of phage’s host specificity will be determined. This study will provide a theoretical basis for phage prevention and control of multidrug resistant bacteria. Completion of this project will also provide significant reference value to study of phage therapy for other pathogens.

近年来，多重耐药菌的不断出现对抗生素治疗提出了严峻的挑战，而噬菌体治疗是细菌预防和治疗的替代方案。其中，有尾噬菌体占噬菌体总量的96%，有尾噬菌体对细菌的吸附依赖于噬菌体尾部蛋白组成的吸附器官与宿主菌表面受体特异性识别，从而引发后续的裂解过程，最终杀死细菌。因此，对噬菌体尾部蛋白的结构和功能的认知是理解噬菌体宿主特异性的重要环节。本研究以三株完全不同的有尾噬菌体为对象，拟通过基因组学、突变文库构建、蛋白表达和纯化、表面等离子共振、基因敲除、截短体构建、定点突变等研究方法，鉴定噬菌体尾部的受体结合蛋白和宿主菌表面受体，验证受体结合蛋白与受体的相互作用，最终，阐述噬菌体尾部蛋白介导噬菌体特异性吸附的分子机制。该研究将为多重耐药菌的噬菌体治疗奠定理论基础，同时，对于其它噬菌体的裂解机制研究也具有借鉴意义。

抗生素耐药菌仍然是常规抗菌感染治疗的一大障碍，所以非抗生素类抗感染药的研究受到了广泛的重视，噬菌体有望成为人类制服病菌的新武器。本研究对多株有尾噬菌体的生物学特征进行了鉴定和系统描述，包括形态学特征鉴定、分类学鉴定、宿主范围、一步生长曲线、宿主范围鉴定等。对多株有尾噬菌体的基因组进行了深度解析和功能注释，对编码的尾部蛋白的基因模块进行了深入分析和比对，对噬菌体的受体结合蛋白和宿主菌表面受体进行了预测和验证，扩展了人们对噬菌体的认知，为多重耐药菌的噬菌体治疗奠定了理论基础，对于其它噬菌体的裂解机制研究也具有重要的借鉴意义。