Bacteriophages suppress CRISPR-Cas immunity using RNA-based anti-CRISPRs.

ABSTRACT: Many bacteria use CRISPR-Cas systems to combat mobile genetic elements, such as bacteriophages and plasmids¹. In turn, these invasive elements have evolved anti-CRISPR proteins to block host immunity^2,3. Here we unveil a distinct type of CRISPR-Cas Inhibition strategy that is based on small non-coding RNA anti-CRISPRs (Racrs). Racrs mimic the repeats found in CRISPR arrays and are encoded in viral genomes as solitary repeat units⁴. We show that a prophage-encoded Racr strongly inhibits the type I-F CRISPR-Cas system by interacting specifically with Cas6f and Cas7f, resulting in the formation of an aberrant Cas subcomplex. We identified Racr candidates for almost all CRISPR-Cas types encoded by a diverse range of viruses and plasmids, often in the genetic co

SUBMITTER: Camara-Wilpert S 

PROVIDER: S-EPMC10651486 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature