Klebsiella Phage ΦK64-1 Encodes Multiple Depolymerases for Multiple Host Capsular Types.

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.