Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal 462066, Madhya Pradesh, India.
Sci Adv. 2024 Feb 9;10(6):eadh9812. doi: 10.1126/sciadv.adh9812.
D29 mycobacteriophage encodes LysA endolysin, which mediates mycobacterial host cell lysis by targeting its peptidoglycan layer, thus projecting itself as a potential therapeutic. However, the regulatory mechanism of LysA during the phage lytic cycle remains ill defined. Here, we show that during D29 lytic cycle, structural and functional regulation of LysA not only orchestrates host cell lysis but also is critical for maintaining phage-host population dynamics by governing various phases of lytic cycle. We report that LysA exists in two conformations, of which only one is active, and the protein undergoes a host peptidoglycan-dependent conformational switch to become active for carrying out endogenous host cell lysis. D29 maintains a pool of inactive LysA, allowing complete assembly of phage progeny, thus helping avoid premature host lysis. In addition, we show that the switch reverses after lysis, thus preventing exogenous targeting of bystanders, which otherwise negatively affects phage propagation in the environment.
D29 分枝杆菌噬菌体编码 LysA 内溶素，它通过靶向其肽聚糖层来介导分枝杆菌宿主细胞裂解，从而成为一种潜在的治疗方法。然而，噬菌体裂解周期中 LysA 的调控机制仍不清楚。在这里，我们表明在 D29 裂解周期中，LysA 的结构和功能调节不仅协调宿主细胞裂解，而且通过控制裂解周期的各个阶段对于维持噬菌体-宿主种群动态也至关重要。我们报告说，LysA 存在两种构象，其中只有一种是活性的，并且该蛋白经历宿主肽聚糖依赖性构象转变以变得活跃，从而进行内源性宿主细胞裂解。D29 维持一个无活性 LysA 池，允许噬菌体后代的完全组装，从而有助于避免过早的宿主裂解。此外，我们表明在裂解后开关会逆转，从而防止对旁观者的外源靶向，否则这会对环境中的噬菌体繁殖产生负面影响。
