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| Title | Protein-templated synthesis of dinucleotide repeat DNA by an antiphage reverse transcriptase. |
|---|---|
| Journal, issue, pages | Science, Page eaed1656, Year 2026 |
| Publish date | Apr 16, 2026 |
Authors | Pujuan Deng / Hyunbin Lee / Carlo Armijo / Haoqing Wang / Alex Gao / ![]() |
| PubMed Abstract | Defense-associated reverse transcriptases (DRTs) are widespread bacterial anti-phage systems that use unconventional mechanisms of polynucleotide synthesis. We show that DRT3, which comprises two ...Defense-associated reverse transcriptases (DRTs) are widespread bacterial anti-phage systems that use unconventional mechanisms of polynucleotide synthesis. We show that DRT3, which comprises two distinct RTs (Drt3a and Drt3b) and a noncoding RNA (ncRNA), synthesizes alternating poly(GT/AC) double-stranded DNA. Cryo-electron microscopy structures at 2.6 Å resolution reveal a D3-symmetric 6:6:6 complex of Drt3a, Drt3b, and ncRNA. Drt3a produces the poly(GT) strand using a conserved ACACAC template within the ncRNA. Notably, Drt3b synthesizes a complementary, protein-primed poly(AC) strand in the complete absence of a nucleic acid template, using conserved active site residues specific to Drt3b to enforce precise base alternation. These findings expand the functional landscape of nucleic acid polymerases, revealing a protein-templated mechanism for sequence-specific DNA synthesis. |
External links | Science / PubMed:41990131 |
| Methods | EM (single particle) |
| Resolution | 2.49 - 3.02 Å |
| Structure data | EMDB-73864: Cryo-EM hexamer map of the elongating EcDRT3 complex EMDB-73865: Cryo-EM hexamer map of the resting EcDRT3 complex ![]() EMDB-75821: Cryo-EM protomer map of the elongating EcDRT3 complex ![]() EMDB-75826: Cryo-EM map of Drt3a and ncRNA in the elongating EcDRT3 complex ![]() EMDB-75828: Cryo-EM protomer map of the resting EcDRT3 complex ![]() EMDB-75830: Cryo-EM map of Drt3a and ncRNA in the resting EcDRT3 complex ![]() EMDB-75981: Cryo-EM map of the EcDRT3 hexameric complex with ddATP and dCTP. ![]() EMDB-75982: Cryo-EM protomer map of the EcDRT3 complex with ddATP and dCTP. ![]() EMDB-75983: Map of the Drt3a-ncRNA subcomplex in the EcDRT3 complex with ddATP and dCTP ![]() EMDB-76001: Composite cryo-EM map of the elongating EcDRT3 complex ![]() EMDB-76002: Composite cryo-EM map of the resting EcDRT3 complex |
| Chemicals | ![]() ChemComp-MG: ![]() ChemComp-POP: ![]() ChemComp-HOH: |
| Source |
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Keywords | IMMUNE SYSTEM / DRT3-ncRNA complex / reverse transcriptase / Anti-phage complex |
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