Abstract
Pseudomonas jumbophage phiKZ is prominent because of the proteinaceous nuclear structure that is formed during the infection cycle, protecting the replicating phage DNA from host nucleases. Progress has been made in deciphering the molecular basis of nucleus formation and other unique aspects of phiKZ biology, but the understanding of how it causes host lysis remains minimal. Here we present bioinformatic, physiological and molecular evidence for a “lysis cassette”, the expression of which is necessary and sufficient for the temporally regulated disruption of the host envelope. This cluster contains genes for the usual components of an MGL (multigene lysis) system, including the holin, endolysin, i-spanin and o-spanin. In addition, a fifth gene in the cluster, encoding a cytoplasmic protein, was found to accelerate the timing of holin-mediated lethality when expressed in trans. Evidence is provided that suggests this lysis regulator protein interacts with the cytoplasmic domain of the phiKZ class III holin. In support of this notion, alpha-fold analysis generated a high-confidence structure of a conserved holin-lysis regulator heterodimer complex. Infections at high multiplicity resulted in slower bulk culture lysis profiles than at low multiplicity, suggesting that phiKZ might have a lysis-inhibition system.
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Data availability
All data supporting the findings of this study are available within the paper and its Supplementary Information. Protein sequences are provided in Figure 1, also available at NC_004629.1. Primer sequences are provided in Supplemental Table 1. Protein sequences used to create multi-sequence alignment are provided in Supplemental data 2 and 3.
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Acknowledgements
The authors would like to thank the funding supported by the National Institute of General Medical Sciences, grant no. R35GM136396 to R.Y. and by the Center for Phage Technology, which is jointly supported by Texas A&M AgriLife Research. We also thank Joseph Bondy-Denomy for kindly sharing phiKZ phage lysates, and the lab of Dr. Urs Jenal at the University of Basel in Switzerland for providing the cumate inducible vector pQFT.
Funding
This work was supported by funding from the National Institute of General Medical Sciences, grant no. R35GM136396 to R.Y. and by the Center for Phage Technology, which is jointly supported by Texas A&M AgriLife Research.
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Conceptualization, P.M., J.W., R.Y.; Data Curation, P.M., J.W.; Formal Analysis, P.M., G.G., K.S., J.W.; Experimental works, P.M., J.W., G.G., K.S.; Investigation, P.M., J.W.; Methodology, P.M., J.W., R.Y.; Resources, P.M., R.Y.; Supervision, R.Y.; Writing – Original Draft, P.M., R.Y.; Writing – Review & Editing, P.M., R.Y.; Validation, P.M., R.Y.; Visualization, P.M.; Project Administration, P.M., R.Y.; Funding Acquisition, R.Y.
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Manohar, P., Wan, J., Ganser, G. et al. The Lysis cassette of jumbophage PhiKZ. Sci Rep (2026). https://doi.org/10.1038/s41598-026-36188-9
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DOI: https://doi.org/10.1038/s41598-026-36188-9
