群体感应是细菌之间进行交流的一种重要方式，细菌通过群体感应调控许多重要生理过程，比如毒力因子的释放、生物膜的形成等。不过关于群体感应的研究主要限于细菌，然而最新研究发现噬菌体中也有群体感应并调控着噬菌体溶原-裂解途径。aimR是噬菌体群体感应系统中的关键蛋白，aimR是否结合多肽决定着噬菌体溶原-裂解途径的选择。然而aimR及其复合物的结构尚未报道，它发挥功能的分子机理还不清楚。我们通过X-ray晶体学技术解析了aimR的结构。为进一步揭示噬菌体群体感应系统工作的分子机理，本项目拟在此基础上解析aimR和调控基因aimX启动子区DNA复合物、aimR和多肽复合物的的晶体结构，在三维结构的指导下，阐明aimR调控噬菌体溶原-裂解途径的分子机理。因此，本研究不仅将丰富我们对群体感应的认识，阐明噬菌体群体感应系统调控噬菌体溶原-裂解途径的分子机理，也将为抗噬菌体污染和噬菌体治疗等提供新的思路。

Quorum sensing is a widespread phenomenon in bacteria used to coordinate gene expression among local bacterial population. The role of quorum sensing in pathogenic bacteria for regulation of genes that promote invasion, defense, and spreading has been particularly well documented. However, the studies on quorum sensing have mostly been focused on bacteria. Recent reports suggest that quorum sensing also exists in bacteriophages, where the quorum sensing system aimR-aimP plays a vital role in the lysogeny-lysis decision. In the aimR-aimP system, aimR is the key protein whose activity becomes inhibited upon peptide binding, which then triggers the entry into the lysogenic cycle. Due to the fact that the molecular basis of bacteriophage quorum sensing system remains largely unknown, we sought to study the aimR-mediated molecular mechanisms of bacteriophage quorum sensing. By solving the structures of aimR-DNA and aimR-peptide complexes, we aim to thoroughly explore these interactions with regard to peptide specificity, regulatory target recognition, and ligand-induced aimR allostery. Using the solved complex structures as a guide, we further plan to elucidate the molecular basis of the lysogeny-lysis decision dependence on aimR among phages. This study will not only broaden our understanding of quorum sensing in bacteriophages, but will also provide better solutions for bacteriophage contamination and new strategies for phage therapy.