Abstract 2396 Visualizing DNA structures that regulate CRISPR adaptation to viral RNA

Archaea and bacteria use CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) systems to defend themselves from phage infection. To acquire immunity to new phages, the CRISPR-associated integrase complex (Cas1-Cas2) captures fragments of foreign nucleic acid and integrates them at the first CRISPR “repeat” within an array. Notably, CRISPR-Cas systems exhibit vast diversity in spacer acquisition mechanisms that reflect complex evolutionary adaptation to viral challenges. This includes RNA-targeting CRISPR systems that possess natural fusions of reverse transcriptases to CRISPR associated integrases (RT/Cas1-Cas2), enabling integration of DNA-based memories of foreign RNA into the CRISPR locus.