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A Noncontiguous Code for RNA-Guided DNA Recognition Preceded CRISPR
Peter H Yoon1,2, Kenneth Loi1,2, Zeyuan Zhang2,3
1Department of Molecular and Cell Biology, University of California, Berkeley; Berkeley, CA, USA.
Biorxiv : the Preprint Server for Biology
|May 7, 2026
Summary
Researchers discovered the ancient Viral Interference Programmable Repeat (VIPR) system, predating CRISPR-Cas. This system uses novel vrRNAs for programmable DNA targeting, offering new genetic control mechanisms and revealing evolutionary roots of adaptive immunity.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- CRISPR-Cas systems provide adaptive immunity via RNA-guided proteins, but their evolutionary origins remain unclear.
- Understanding the ancient mechanisms of adaptive immunity can illuminate fundamental biological processes.
Purpose of the Study:
- To discover and characterize novel systems related to adaptive immunity.
- To investigate the evolutionary history and functional mechanisms of ancient defense systems against viruses.
Main Methods:
- Discovery and characterization of the Viral Interference Programmable Repeat (VIPR) system.
- Analysis of vrRNA structure and function in recognizing double-stranded DNA.
- Demonstration of programmable phage defense using the VIPR system.
Main Results:
- Identified VIPR systems, comprising ancient Vipr proteins and vrRNAs with unique GGY/NN motifs.
- vrRNAs recognize double-stranded DNA via a noncontiguous code, distinct from canonical guide RNAs.
- VIPR systems target competing phages, enabling programmable defense and transcriptional repression.
Conclusions:
- The VIPR system represents an ancient form of adaptive immunity, predating CRISPR-Cas.
- VIPR systems reveal a novel logic for programmable genetic control through gapped DNA recognition.
- The evolutionary roots of adaptive immunity are linked to ancient viral warfare.
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