Mosterd Cas, Grafakou Andriana, Ortiz Charneco Guillermo, de Waal Paul P, van Rijswijck Irma M H, van Peij Noël N M E, Péchoux Christine, Kulakauskas Saulius, Cambillau Christian, Mahony Jennifer, van Sinderen Douwe
School of Microbiology and Alimentary Pharmabiotics Centre (APC) Microbiome Ireland, University College Cork, Cork T12 YT20, Ireland.
Dutch State Mines-Firmenich, Taste, Texture and Health, Center for Food Innovation, Delft 2613 AX, The Netherlands.
Proc Natl Acad Sci U S A. 2025 Jun 17;122(24):e2426508122. doi: 10.1073/pnas.2426508122. Epub 2025 Jun 11.
In recent years, the number of newly discovered systems that bacteria use to combat bacteriophages is increasing at an impressive rate. To obtain mechanistic insights into several antiphage systems identified in previous studies, we isolated 66 phage escape mutants which had become insensitive to 13 distinct, plasmid-encoded lactococcal phage resistance systems (i.e. Rhea, Kamadhenu, Rugutis, Audmula, PARIS, type II CBASS, Septu, AbiA, AbiB, AbiD/F, AbiG, AbiJ, AbiP). Genome analysis of these phage escape mutants identified a total of 15 mutated genes. Six of the encoded proteins appear to activate specific antiphage systems. Furthermore, AbiA escape mutants were found to be insensitive to AbiJ, while distinct antiphage systems (AbiG and AbiP) were observed to be activated by a major phage tail protein, indicating mechanistic commonalities. PARIS homologues encoded by members of different bacterial genera appear to share similar sensing mechanisms, whereas our data indicate mechanistic differences between Septu homologues from different genera. Based on our escape mutant sequence analysis, previously predicted domains, and experimental data using the purified endolysin of phage c2, we propose that Audmula modifies the cell wall of the host bacterium, delaying cell lysis and release of progeny phages, protecting the host cell by a heretofore unknown mode of action. The obtained advances in our understanding of lactococcal antiphage mechanisms provide fundamental insights into phage-host interactions, which undoubtedly benefits the dairy industry but may also be useful for biotechnological or biomedical applications.
近年来，细菌用于对抗噬菌体的新发现系统数量正以惊人的速度增加。为了深入了解先前研究中鉴定出的几种抗噬菌体系统的机制，我们分离出了66个噬菌体逃逸突变体，这些突变体对13种不同的、质粒编码的乳球菌噬菌体抗性系统（即Rhea、Kamadhenu、Rugutis、Audmula、PARIS、II型CBASS、Septu、AbiA、AbiB、AbiD/F、AbiG、AbiJ、AbiP）不再敏感。对这些噬菌体逃逸突变体的基因组分析共鉴定出15个突变基因。其中六个编码蛋白似乎能激活特定的抗噬菌体系统。此外，发现AbiA逃逸突变体对AbiJ不敏感，同时观察到不同的抗噬菌体系统（AbiG和AbiP）被一种主要的噬菌体尾蛋白激活，这表明存在机制上的共性。不同细菌属成员编码的PARIS同源物似乎具有相似的传感机制，而我们的数据表明不同属的Septu同源物之间存在机制差异。基于我们对逃逸突变体的序列分析、先前预测的结构域以及使用噬菌体c2纯化的内溶素的实验数据，我们提出Audmula修饰宿主细菌的细胞壁，延迟细胞裂解和子代噬菌体的释放，通过一种迄今未知的作用方式保护宿主细胞。我们在理解乳球菌抗噬菌体机制方面取得的进展为噬菌体 - 宿主相互作用提供了基本见解，这无疑有益于乳制品行业，但也可能对生物技术或生物医学应用有用。
