A Reverse Transcriptase-Cas1 Fusion Protein Contains a Cas6 Domain Required for Both CRISPR RNA Biogenesis and RNA Spacer Acquisition (Molecular Cell)

CRISPR RNAs target the CRISPR-Cas immune machinery to invasive nucleic acids. Mohr et al. describe a single Cas enzyme with three biochemical activities (CRISPR RNA processing, reverse transcriptase, and spacer integration) that unite the separate functions of adapting to RNA and DNA invaders and creating molecular guides for combating future infections.