CRISPRi targeting to the Neisseria gonorrhoeae R-loop or G4 mutant region restores pilin antigenic variation.

CRISPRi targeting to specific loci restores pilin antigenic variation in Neisseria gonorrhoeae by replacing R-loop and G4 structures, revealing topological stress as a key factor.

• Why it matters: Understanding the mechanisms behind pilin antigenic variation is crucial because it enables N. gonorrhoeae to evade immune responses, yet the triggers initiating this process remain unclear.
• What they did: The study used a Type I-C CRISPR interference complex to target mutant garP or G4 loci, with 16 targeted sites, demonstrating that precise strand and position targeting restored antigenic variation and viability.
• The result: Findings show that the position and strand of R-loop formation, rather than specific sequences, determine cell viability and antigenic variation, highlighting localized topological stress as a driver of genome dynamics.