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Updated: May 9, 2025

Bacterial Artificial Chromosomes: A Functional Genomics Tool for the Study of Positive-strand RNA Viruses
Published on: December 29, 2015
Bacterial reverse transcriptase synthesizes long poly(A)-rich cDNA for antiphage defense
Xin-Yi Song1, Yushan Xia1, Jun-Tao Zhang1
1Department of Biochemistry, SUSTech Homeostatic Medicine Institute, School of Medicine, Southern University of Science and Technology, Shenzhen, China.
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 noncoding RNA (ncRNA) to mediate antiphage defense by inducing cell growth arrest through abortive infection. Upon phage infection, the phage-encoded ribonucleotide reductase NrdAB complex increases intracellular deoxyadenosine triphosphate levels, activating DRT9 to synthesize long, polyadenylate [poly(A)]-rich single-stranded complementary DNA (cDNA), which likely sequesters the essential phage single-stranded DNA binding (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.
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