Tan Demeng, Zhang Yiyuan, Qin Jinhong, Le Shuai, Gu Jingmin, Chen Li-Kuang, Guo Xiaokui, Zhu Tongyu
Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China.
Institutes of Medical Sciences, Shanghai Jiao Tong University, Shanghai 200025, China.
Microorganisms. 2020 Mar 7;8(3):378. doi: 10.3390/microorganisms8030378.
Phage therapy is a potential and promising avenue for controlling the emergence and spread of multidrug-resistant (MDR) , however, the rapid development of anti-phage resistance has been identified as an obstacle to the development of phage therapy. Little is known about the mechanism employed by MDR strains and how they protect themselves from lytic phage predation in vitro and in vivo. In this study, comparative genomic analysis shows undecaprenyl-phosphate glucose-1-phosphate transferase (WcaJ), the initial enzyme catalyzing the biosynthesis of colanic acid, is necessary for the adsorption of phage 117 () to the host strain Kp36 to complete its lytic life cycle. In-frame deletion of alone was sufficient to provide phage 117 resistance in the Kp36 wild-type strain. Complementation assays demonstrated the susceptibility of phage 117, and the mucoid phenotype could be restored in the resistant strain Kp36-117R by expressing the wild-type version of . Remarkably, we found that bacterial mobile genetic elements ( and ) block phage 117 infections by disrupting the coding region of , thus preventing phage adsorption to its phage receptor. Further, we revealed that the wcaJ mutation likely occurred spontaneously rather than adapted by phage 117 predation under unfavorable environments. Taken together, our results address a crucial evolutionary question around the mechanisms of phage-host interactions, increasing our current understandings of anti-phage defense mechanisms in this important MDR pathogen.
噬菌体疗法是控制多重耐药（MDR）菌出现和传播的一种潜在且有前景的途径，然而，抗噬菌体耐药性的快速发展已被确定为噬菌体疗法发展的一个障碍。关于MDR菌株所采用的机制以及它们在体外和体内如何保护自己免受裂解性噬菌体捕食知之甚少。在本研究中，比较基因组分析表明，十一异戊烯基磷酸葡萄糖-1-磷酸转移酶（WcaJ）是催化柯氏酸生物合成的初始酶，它对于噬菌体117吸附到宿主菌株Kp36以完成其裂解生命周期是必需的。单独进行框内缺失就足以使Kp36野生型菌株对噬菌体117产生抗性。互补试验证明了噬菌体117的敏感性，并且通过表达野生型的WcaJ可以使耐药菌株Kp36 - 117R恢复黏液样表型。值得注意的是，我们发现细菌移动遗传元件（ISKpn6和Tn6548）通过破坏WcaJ的编码区域来阻断噬菌体117感染，从而防止噬菌体吸附到其噬菌体受体上。此外，我们揭示了wcaJ突变可能是自发发生的，而不是在不利环境下通过噬菌体117捕食而产生适应性变化。综上所述，我们的研究结果解决了一个围绕噬菌体 - 宿主相互作用机制的关键进化问题，增进了我们目前对这种重要MDR病原体中抗噬菌体防御机制的理解。
