Structure of the IscB–ωRNA ribonucleoprotein complex, the likely ancestor of CRISPR-Cas9
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Published version
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Author(s)
Kato, Kazuki
Okazaki, Sae
Kannan, Soumya
Altae-Tran, Han
Esra Demircioglu, F
Isayama, Yukari
Ishikawa, Junichiro
Fukuda, Masahiro
Macrae, Rhiannon K
Nishizawa, Tomohiro
Date Issued
November 7, 2022
Journal
Nature Communications
Publisher
Springer Science and Business Media LLC
Citation
Kato, Kazuki, Okazaki, Sae, Kannan, Soumya, Altae-Tran, Han, Esra Demircioglu, F et al. 2022. "Structure of the IscB–ωRNA ribonucleoprotein complex, the likely ancestor of CRISPR-Cas9." Nature Communications, 13 (1).
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Final published version
Abstract
AbstractTransposon-encoded IscB family proteins are RNA-guided nucleases in the OMEGA (obligate mobile element-guided activity) system, and likely ancestors of the RNA-guided nuclease Cas9 in the type II CRISPR-Cas adaptive immune system. IscB associates with its cognate ωRNA to form a ribonucleoprotein complex that cleaves double-stranded DNA targets complementary to an ωRNA guide segment. Although IscB shares the RuvC and HNH endonuclease domains with Cas9, it is much smaller than Cas9, mainly due to the lack of the α-helical nucleic-acid recognition lobe. Here, we report the cryo-electron microscopy structure of an IscB protein from the human gut metagenome (OgeuIscB) in complex with its cognate ωRNA and a target DNA, at 2.6-Å resolution. This high-resolution structure reveals the detailed architecture of the IscB–ωRNA ribonucleoprotein complex, and shows how the small IscB protein assembles with the ωRNA and mediates RNA-guided DNA cleavage. The large ωRNA scaffold structurally and functionally compensates for the recognition lobe of Cas9, and participates in the recognition of the guide RNA–target DNA heteroduplex. These findings provide insights into the mechanism of the programmable DNA cleavage by the IscB–ωRNA complex and the evolution of the type II CRISPR-Cas9 effector complexes.
MIT Department
Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences
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DOI of Published Version
https://doi.org/10.1038/s41467-022-34378-3
