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Updated: Jun 26, 2025
15:49
Reverse Genetics to Engineer Positive-Sense RNA Virus Variants
Published on: June 9, 2022
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De novo gene synthesis by an antiviral reverse transcriptase
Stephen Tang1, Valentin Conte1, Dennis J Zhang2
1Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
Biorxiv : the Preprint Server for Biology
|May 20, 2024
Summary
Bacteria use defense-associated reverse transcriptase 2 (DRT2) systems to synthesize new genes from RNA. This process creates a novel protein that halts bacterial growth, offering a unique defense against viruses.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacteria possess diverse immune systems targeting foreign nucleic acids to combat viral infections.
- Defense-associated reverse transcriptase (DRT) systems represent an alternative bacterial defense strategy utilizing DNA synthesis.
- The specific DNA products and functions of DRT systems, particularly DRT2, remain largely uncharacterized.
Approach:
- Investigated DRT2 systems using unbiased profiling of RNA and DNA ligands in DRT2-expressing cells.
- Analyzed the mechanism of de novo gene synthesis via rolling-circle reverse transcription of non-coding RNA (ncRNA).
- Examined the role of phage presence in triggering second-strand cDNA synthesis and subsequent gene expression.
Key Points:
- DRT2 systems synthesize DNA from ncRNA through rolling-circle reverse transcription with programmed template jumping.
- Phage presence induces the production of double-stranded DNA, which is transcribed into messenger RNA.
- This results in a novel, stop codon-less open reading frame (neo) encoding a protein that causes potent growth arrest.
Conclusions:
- DRT2 systems employ a unique immunity mechanism involving RNA-templated de novo gene synthesis.
- The study reveals a novel expansion of coding potential and challenges traditional views of genetic information.
- Rolling-circle reverse transcription and Neo protein function are broadly conserved across diverse DRT2 homologs.
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