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bioRxiv · 10.64898/2026.11.03.763826

Structural basis of ribosomal RNA repair by RtcB2

Tian, Y.·Zhou, Q.·Yu, Q.·Huang, Y.·Zhang, W.·Huang, J.·Yu, T.·Zeng, F.
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Abstract

Ribotoxins disable ribosomes by cleaving ribosomal RNA, but how repair enzymes recognize and restore these damaged machines remains unclear. Here, we report three cryo-electron microscopy structures of the RNA ligase RtcB2 bound to damaged Escherichia coli 30S subunits. An extended interface stabilizes the ribosomal head and decoding-center scaffold while positioning the cleaved 3'-phosphate end within the catalytic pocket. Two structures contain enzyme-linked guanosine monophosphate, whereas the third captures its transfer to the RNA. RNA activation accompanies RtcB2 reorientation and entry of the 5'-hydroxyl-containing segment into an adjacent cleft. Comparisons with assembled ribosomes reveal structural barriers to substrate access. These structures connect recognition of a damaged ribosome to chemical activation of its RNA for repair.

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Tian, Y., Zhou, Q., Yu, Q., Huang, Y., Zhang, W., Huang, J., Yu, T., Zeng, F.. 2026-11-04. Structural basis of ribosomal RNA repair by RtcB2. https://doi.org/10.64898/2026.11.03.763826

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