Phage proofing Pseudomonas putida uncovers novel broad-spectrum phage resistance protein Psh
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…
Phage resistance plays a crucial role in safeguarding bacterial cultures during biomanufacturing, although the mechanisms behind it are often unclear and may negatively impact the bacteria's fitness. Researchers generated two strains of Pseudomonas putida capable of resisting at least six different phage types through experimental evolution.
Sequencing the genomes of these strains revealed a single frameshift deletion in each that reactivated a Type I secretion system (T1SS) ATPase. Additionally, there was a notable increase in the transcription of a nearby gene, PP_1794, which encodes a protein dubbed Phage shielding helix rich protein (Psh). Experiments demonstrated that Psh is secreted by the restored T1SS, providing comprehensive protection against phages.
Despite no growth or expression issues in the modified P. putida compared to its wild-type counterpart, the phage-resistant strain exhibited lower levels of pyoverdine production. The Psh gene and the T1SS are found in various Gram-negative bacteria, indicating the presence of an uncharacterized phage defense system in P. putida based on the secretion-mediated masking of receptors.
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