Acquisition of novel arrays via horizontal gene transfer rewires CRISPR-mediated defense in Pseudomonas aeruginosa.

Horizontal gene transfer of isolated CRISPR arrays in Pseudomonas aeruginosa rewires CRISPR-mediated immunity and promotes pan-immunity.

• Why it matters: Understanding the function and evolution of isolated CRISPR arrays is crucial because they may serve as mobile genetic elements that influence bacterial immune responses and adaptability, yet their significance has been unclear.
• What they did: Researchers characterized the type I-F CRISPR-Cas system in P. aeruginosa ATCC 10145, analyzing 1,196 genomes to identify isolated CRISPR arrays, their association with mobile elements, and their horizontal transfer dynamics.
• The result: Isolated CRISPR3 arrays are actively transferred across genomes, undergo hyperactive primed adaptation, and act as gateways for mobilizing immunological memory, enabling CRISPR pan-immunity in P. aeruginosa.