9IOA

Cryo-EM structure of the tetrameric DRT9-ncRNA complex

Summary for 9IOA

• Entry DOI: 10.2210/pdb9ioa/pdb
• EMDB information: 60724
• Descriptor: RNA (177-MER), RNA-dependent DNA polymerase (2 entities in total)
• Functional Keywords: rna binding, protein-rna complex, antiviral protein/rna, antiviral protein-rna complex
• Biological source: Escherichia coli; More
• Total number of polymer chains: 8
• Total formula weight: 460449.02

Authors

Zhang, J.T.,Song, X.Y.,Wei, X.Y.,Jia, N. (deposition date: 2024-07-08, release date: 2025-05-14)

Primary citation

Song, X.Y.,Xia, Y.,Zhang, J.T.,Liu, Y.J.,Qi, H.,Wei, X.Y.,Hu, H.,Xia, Y.,Liu, X.,Ma, Y.F.,Jia, N.
Bacterial reverse transcriptase synthesizes long poly-A-rich cDNA for antiphage defense.
Science, :eads4639-eads4639, 2025

PubMed Abstract: Prokaryotic defense-associated reverse transcriptases (DRTs) were recently identified with antiviral functions; however, their functional mechanisms remain largely unexplored. Here we show that DRT9 forms a hexameric complex with its upstream non-coding RNA (ncRNA) to mediate antiphage defense by inducing cell growth arrest via abortive infection. Upon phage infection, the phage-encoded ribonucleotide reductase NrdAB complex elevates intracellular dATP levels, activating DRT9 to synthesize long, poly-A-rich single-stranded cDNA, which likely sequesters the essential phage SSB protein and disrupts phage propagation. We further determined the cryo-electron microscopy structure of the DRT9-ncRNA hexamer complex, providing mechanistic insights into its cDNA synthesis. These findings highlight the diversity of RT-based antiviral defense mechanisms, expand our understanding of RT biological functions, and provide a structural basis for developing DRT9-based biotechnological tools.

PubMed: 40310939
DOI: 10.1126/science.ads4639

Experimental method

ELECTRON MICROSCOPY (2.59 Å)