Cryo-EM structure of the RADAR supramolecular anti-phage defense complex

Duncan-Lowey, B.; Tal, N.; Johnson, A. G.; Rawson, S.; Mayer, M. L.; Doron, S.; Millman, A.; Melamed, S.; Fedorenko, T.; Kacen, A.; Amitai, G.; Sorek, R.; Kranzusch, P. J.

doi:10.1101/2022.08.17.504323

bioRxiv · 10.1101/2022.08.17.504323

Cryo-EM structure of the RADAR supramolecular anti-phage defense complex

Duncan-Lowey, B.·Tal, N.·Johnson, A. G.·Rawson, S.·Mayer, M. L.·Doron, S.·Millman, A.·Melamed, S.·Fedorenko, T.·Kacen, A.·Amitai, G.·Sorek, R.·Kranzusch, P. J.

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Abstract

RADAR is a two-protein bacterial defense system which was reported to defend against phage by editing messenger RNA. Here we determine cryo-EM structures of the RADAR defense complex, revealing RdrA as a heptameric, two-layered AAA+ ATPase and RdrB as a dodecameric, hollow complex with twelve surface-exposed deaminase active sites. RdrA and RdrB join to form a giant assembly up to 10 MDa, with RdrA docked as a funnel over the RdrB active site. Surprisingly, our structures reveal a RdrB active site that targets mononucleotides, not RNA. We show that RdrB catalyzes ATP-to-ITP conversion in vitro and induces the accumulation of inosine mononucleotides during phage infection in vivo, limiting phage replication. Our results define ATP mononucleotide deamination as a determinant of RADAR immunity and reveal supramolecular assembly of a nucleotide-modifying machine as a novel mechanism of anti-phage defense.

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Duncan-Lowey, B., Tal, N., Johnson, A. G., Rawson, S., Mayer, M. L., Doron, S., Millman, A., Melamed, S., Fedorenko, T., Kacen, A., Amitai, G., Sorek, R., Kranzusch, P. J.. 2022-08-18. Cryo-EM structure of the RADAR supramolecular anti-phage defense complex. https://doi.org/10.1101/2022.08.17.504323

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