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bioRxiv · 10.64898/2026.09.02.748959

Phage proofing Pseudomonas putida uncovers novel broad-spectrum phage resistance protein Psh

Diaz, B.·Won, S.·Jaryenneh, J. D.·Rahman, M. M.·Chourasia, V. R.·Mageeney, C. M.
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Abstract

Broad-spectrum phage resistance offers an important layer of protection against bacterial fermenter crashes during biomanufacturing processes, yet the underlying mechanisms are often poorly defined or come at a fitness cost. Using experimental evolution, we generated two Pseudomonas putida strains that were resistant to at least six phage genera. Genome sequencing revealed a single frameshift deletion in each strain that restored functionality of a Type I secretion system (T1SS) ATPase. We also found strong transcriptional upregulation of a nearby protein, PP_1794, which we coin Phage shielding helix rich protein (Psh). Overexpression experiments show that Psh protein is secreted by this restored T1SS to confer complete phage resistance. When compared to wild-type P. putida KT2440, no growth or expression defects were evident, but pyoverdine production was reduced. The Psh gene and T1SS are widely distributed across Gram-negative bacteria. These findings uncover a previously uncharacterized phage defense system in P. putida based on secretion-mediated receptor masking.

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Diaz, B., Won, S., Jaryenneh, J. D., Rahman, M. M., Chourasia, V. R., Mageeney, C. M.. 2026-09-03. Phage proofing Pseudomonas putida uncovers novel broad-spectrum phage resistance protein Psh. https://doi.org/10.64898/2026.09.02.748959

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