The study of bacteriophage-host interactions has yielded insights into the basic biology of many bacterial
pathogens; however, our understanding of these relationships in Klebsiella spp. is limited. In this study, a
proteomic analysis of the novel temperate Klebsiella bacteriophage, NAR688, revealed that the bacteriophage
encodes a pore-forming bacteriocin (toxin) we call telocin A. Purified telocin A was shown to have bactericidal
activity against a large number of Klebsiella strains. The outer membrane porin, OmpK36, was shown to be
essential for telocin A sensitivity in target cells. We further identified the cognate telocin A immunity protein
and found it to be localized to the inner membrane of Klebsiella cells through sucrose gradient fractionation of
purified cell membranes. To investigate the broader relevance of the bacteriocin-bacteriophage relationship in
Klebsiella, the genomic contexts of other bacteriocins of Klebsiella were analyzed, revealing that bacteriocin-
bacteriophage associations are common in the genus. In future work, the potential evolutionary benefits
conferred to host cells by NAR688 lysogeny will be examined through fitness and competition experiments.
Additionally, four novel bacteriocins (telocins B, C, D and E) identified in the genomes of other, related
temperate bacteriophages will be purified and assessed alone and in combination with telocin A for their ability
to kill different strains of Klebsiella. The findings will provide insights into the abundance and classification of
bacteriophage-encoded bacteriocins, and their potential applications in the treatment of Klebsiella infections.
This study represents the first functional characterisation of non-peptide bacteriocins of bacteriophage origin.