Pan Yi-Jiun, Lin Tzu-Lung, Chen Ching-Ching, Tsai Yun-Ting, Cheng Yi-Hsiang, Chen Yi-Yin, Hsieh Pei-Fang, Lin Yi-Tsung, Wang Jin-Town
Department of Microbiology, School of Medicine, China Medical University, Taichung, Taiwan.
Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan.
J Virol. 2017 Feb 28;91(6). doi: 10.1128/JVI.02457-16. Print 2017 Mar 15.
The genome of the multihost bacteriophage ΦK64-1, capable of infecting capsular types K1, K11, K21, K25, K30, K35, K64, and K69, as well as new capsular types KN4 and KN5, was analyzed and revealed that 11 genes (, , , , , , , , , , and ) encode proteins with amino acid sequence similarity to tail fibers/spikes or lyases. previously was shown to encode a K64 capsule depolymerase (K64dep). Specific capsule-degrading activities of an additional eight putative capsule depolymerases (S2-4 against K1, S1-1 against K11, S1-3 against K21, S2-2 against K25, S2-6 against K30/K69, S2-3 against K35, S1-2 against KN4, and S2-1 against KN5) was demonstrated by expression and purification of the recombinant proteins. Consistent with the capsular type-specific depolymerization activity of these gene products, phage mutants of , , , or lost infectivity for KN4, K25, K35, or K30/K69, respectively, indicating that capsule depolymerase is crucial for infecting specific hosts. In conclusion, we identified nine functional capsule depolymerase-encoding genes in a bacteriophage and correlated activities of the gene products to all ten hosts of this phage, providing an example of type-specific host infection mechanisms in a multihost bacteriophage. We currently identified eight novel capsule depolymerases in a multihost bacteriophage and correlated the activities of the gene products to all hosts of this phage, providing an example of carriage of multiple depolymerases in a phage with a wide capsular type host spectrum. Moreover, we also established a recombineering system for modification of bacteriophage genomes and demonstrated the importance of capsule depolymerase for infecting specific hosts. Based on the powerful tool for modification of phage genome, further studies can be conducted to improve the understanding of mechanistic details of phage infection. Furthermore, the newly identified capsule depolymerases will be of great value for applications in capsular typing.
多宿主噬菌体ΦK64-1能够感染K1、K11、K21、K25、K30、K35、K64和K69血清型，以及新的血清型KN4和KN5。对其基因组进行分析后发现，有11个基因（、、、、、、、、、和）编码的蛋白质，其氨基酸序列与尾丝/刺突或裂解酶具有相似性。此前已证明编码一种K64荚膜解聚酶（K64dep）。通过重组蛋白的表达和纯化，证实了另外8种假定的荚膜解聚酶（S2-4针对K1，S1-1针对K11，S1-3针对K21，S2-2针对K25，S2-6针对K30/K69，S2-3针对K35，S1-2针对KN4，S2-1针对KN5）具有特异性的荚膜降解活性。与这些基因产物的血清型特异性解聚活性一致，、、或的噬菌体突变体分别对KN4、K25、K35或K30/K69失去感染性，这表明荚膜解聚酶对于感染特定宿主至关重要。总之，我们在一种噬菌体中鉴定出9个功能性荚膜解聚酶编码基因，并将这些基因产物的活性与该噬菌体的所有10种宿主相关联，为多宿主噬菌体中血清型特异性宿主感染机制提供了一个例子。我们目前在一种多宿主噬菌体中鉴定出8种新型荚膜解聚酶，并将这些基因产物的活性与该噬菌体的所有宿主相关联，为具有广泛血清型宿主谱的噬菌体中携带多种解聚酶提供了一个例子。此外，我们还建立了一种用于修饰噬菌体基因组的重组工程系统，并证明了荚膜解聚酶对于感染特定宿主的重要性。基于这种强大的噬菌体基因组修饰工具，可以开展进一步研究，以增进对噬菌体感染机制细节的理解。此外，新鉴定出的荚膜解聚酶在血清型分型应用中将具有重要价值。
