Related Experiment Video
Updated: Apr 18, 2026
08:14
Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins
Published on: February 25, 2017
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Protein-templated synthesis of dinucleotide repeat DNA by an antiphage reverse transcriptase
Pujuan Deng1,2, Hyunbin Lee1,2, Carlo Armijo1,3
1Department of Biochemistry, Stanford University, Stanford, CA, USA.
Science (New York, N.Y.)
|April 16, 2026
Summary
Bacterial defense-associated reverse transcriptases (DRTs) create alternating DNA. DRT3 uses a protein-templated mechanism for DNA synthesis, expanding polymerase functions.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- Defense-associated reverse transcriptases (DRTs) are bacterial anti-phage systems.
- DRTs utilize unconventional mechanisms for polynucleotide synthesis.
- DRT3 comprises two reverse transcriptases (Drt3a, Drt3b) and a noncoding RNA (ncRNA).
Purpose of the Study:
- To elucidate the mechanism of DNA synthesis by DRT3.
- To determine the structure of the DRT3 complex.
- To understand the protein-templated DNA synthesis mechanism.
Main Methods:
- Cryo-electron microscopy (Cryo-EM) at 2.6 Å resolution.
- Structural analysis of the Drt3a, Drt3b, and ncRNA complex.
- Biochemical assays to study enzyme activity.
Main Results:
- Determined the D3-symmetric 6:6:6 complex structure of DRT3.
- Drt3a synthesizes a poly(GT) strand using an ncRNA template.
- Drt3b synthesizes a complementary poly(AC) strand via a protein-templated mechanism without a nucleic acid template.
Conclusions:
- DRT3 synthesizes alternating poly(GT/AC) double-stranded DNA.
- Revealed a novel protein-templated DNA synthesis mechanism by Drt3b.
- Expanded the known functional diversity of nucleic acid polymerases.
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