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bioRxiv · 10.64898/2026.03.19.712971

Architecture of a DNA-guided Cas12a

Ocampo, R. F.·Orosco, C.·Huang, B.·West, M. S.·Jain, P. K.·Taylor, D. W.
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Abstract

CRISPR/Cas systems have largely been restricted to RNA-guided nucleases. Here, we present the cryo-EM structure of Acidaminococcus sp. Cas12a (AsCas12a) bound to a pseudo-DNA ({Psi}DNA) guide and RNA target, revealing how Cas12a accomplishes DNA-guided RNA recognition. The {Psi}DNA hairpin bridges the recognition and nuclease lobes, mimicking a PAM-proximal duplex and positioning the spacer to allow formation of a canonical RNA-DNA heteroduplex along the REC lobe. This provides a structural framework for its activity and provides a blueprint for future engineering.

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Ocampo, R. F., Orosco, C., Huang, B., West, M. S., Jain, P. K., Taylor, D. W.. 2026-03-20. Architecture of a DNA-guided Cas12a. https://doi.org/10.64898/2026.03.19.712971

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