RNA-triggered Cas12a2 antibacterial activity and resistance plasmid degradation

Antimicrobial resistance (AMR) demands innovative antibacterial approaches with unique mechanisms. Researchers examined an inducible intracellular CRISPR/Cas12a2 system in modified Escherichia coli designed to target a chloramphenicol-resistant (Chl) transcript. Activation of Cas12a2 considerably slowed bacterial growth and decreased colony-forming units (CFU) by 3-log10 in a laboratory setting, while also reducing bacterial presence in a mouse skin wound experiment.

Investigating the system's impact at a genetic level, the researchers discovered an increase in the expression of recA, a crucial component of the SOS response. Consequently, they developed a Chl-recA dual-targeting construct, which demonstrated a more substantial growth delay compared to single-targeting versions. This enhanced system achieved approximately a 4-log10 reduction in bacterial presence in living organisms.

Additionally, the researchers performed exploratory quantitative polymerase chain reaction (qPCR) on culture supernatants, which indicated a decrease in recoverable plasmid DNA, potentially linked to the treatment. Overall, this study presents preliminary evidence for resistance-transcript-guided Cas12a2 antibacterial activity, emphasizing the potential of targeting stress-associated transcripts to improve programmable antimicrobials.