A leader-repeat hairpin blocks extraneous CRISPR RNA production in diverse CRISPR-Cas13 systems
Angela Migur·Chase L. Beisel·Can Liao·Omer S. Alkhnbashi·Adrien Chauvier·Nils G Walter·Rolf Backofen·Zasha Weinberg·Maximilian Feussner
Abstract CRISPR RNAs (crRNAs) guide recognition and targeting of intracellular invaders as part of adaptive immunity by CRISPR-Cas systems. crRNAs are transcribed from CRISPR arrays of conserved repeats interlaced with invader-derived spacers. While crRNA production is essential for immunity, its optimization for defense remains poorly understood. Here, we show that, in diverse RNA-targeting type VI CRISPR-Cas systems, the leader RNA encoded upstream of the CRISPR array prevents formation of an