Structure of the DNA-guided Cas12a protein

The cryo-electron microscopy structure of Acidaminococcus sp. Cas12a reveals its ability to recognize RNA using a pseudo-DNA guide.

• Cas12a uses a pseudo-DNA hairpin to bridge its recognition and nuclease lobes.
• This structure mimics a DNA duplex, facilitating RNA-DNA pairing.
• The positioning of the spacer allows for the formation of a canonical RNA-DNA heteroduplex.
• The findings provide a structural framework for understanding Cas12a's activity.
• This work may inform future engineering of CRISPR systems.

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