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Klebsiella Phage ΦK64-1 Encodes Multiple Depolymerases for Multiple Host Capsular Types
Yi-Jiun Pan1, Tzu-Lung Lin2, Ching-Ching Chen2
1Department of Microbiology, School of Medicine, China Medical University, Taichung, Taiwan.
Abstract:
The genome of the multihost bacteriophage ΦK64-1, capable of infecting Klebsiella 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 (S1-1, S1-2, S1-3, S2-1, S2-2, S2-3, S2-4, S2-5, S2-6, S2-7, and S2-8) encode proteins with amino acid sequence similarity to tail fibers/spikes or lyases. S2-5 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 S1-2, S2-2, S2-3, or S2-6 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.IMPORTANCE We currently identified eight novel capsule depolymerases in a multihost Klebsiella 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 Klebsiella 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 Klebsiella phage infection. Furthermore, the newly identified capsule depolymerases will be of great value for applications in capsular typing.
Insights
This study identified nine functional capsule depolymerase genes in a multihost bacteriophage, demonstrating their crucial role in infecting specific Klebsiella hosts. Eight novel depolymerases were discovered, advancing phage-based applications.
Area of Science:
- Microbiology
- Virology
- Genomics
Background:
- Bacteriophages are viruses that infect bacteria, playing roles in microbial ecology and potential therapeutic agents.
- Multihost bacteriophages, capable of infecting diverse bacterial strains, offer complex infection mechanisms.
- Klebsiella pneumoniae is an opportunistic pathogen, and its capsular type influences virulence and phage susceptibility.
Purpose of the Study:
- To analyze the genome of bacteriophage ΦK64-1, a multihost phage infecting various Klebsiella capsular types.
- To identify and characterize genes encoding capsule depolymerases responsible for host specificity.
- To demonstrate the functional importance of these depolymerases in phage infection and establish a phage genome modification system.
Main Methods:
- Genomic analysis of bacteriophage ΦK64-1 to identify potential depolymerase genes.
- Expression and purification of recombinant proteins from putative depolymerase genes.
- In vitro assays to demonstrate capsule-degrading activity against specific Klebsiella capsular types.
- Construction and analysis of phage mutants to assess the role of depolymerases in host infectivity.
Main Results:
- Eleven genes encoding proteins with similarity to tail fibers, spikes, or lyases were identified in the ΦK64-1 genome.
- Nine functional capsule depolymerase genes were confirmed, including eight novel ones, with specific activities against ten Klebsiella capsular types (K1, K11, K21, K25, K30, K35, K64, K69, KN4, KN5).
- Phage mutants lacking specific depolymerase genes showed reduced or lost infectivity for corresponding capsular types, confirming the essential role of depolymerases in host recognition and infection.
Conclusions:
- Bacteriophage ΦK64-1 possesses nine functional capsule depolymerases, enabling it to infect a wide range of Klebsiella capsular types.
- Capsule depolymerases are critical for the type-specific infection mechanism of this multihost bacteriophage.
- The identification of novel depolymerases and the establishment of a phage genome modification system provide valuable tools for understanding phage-host interactions and for potential applications in bacterial typing.
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