# Molecular basis for CRISPR RNA-guided nucleic acid cleavage and DNA transposition

> **NIH NIH R01** · PURDUE UNIVERSITY · 2021 · $98,922

## Abstract

PROJECT SUMMARY
The CRISPR-Cas systems provide adaptive immunity in bacteria and archaea by employing guide RNAs and
endonuclease effectors to specifically recognize and cleave invasive nucleic acids. The specific DNA targeting
and cleavage activities of CRISPR-Cas systems have been adopted and developed for genome editing and
various other applications, which are revolutionizing biomedical research and beyond. However, safety
concerns are raised because of off-target genome editing and the dependence on endogenous DNA repair
pathways, hindering clinical applications of CRISPR-Cas systems. Exploration of alternative CRISPR-Cas
systems in nature not only offers an opportunity to overcome those challenges, but may also inspires new
applications. Structural and biochemical characterizations of CRISPR-Cas systems are critical for
understanding of their mechanisms and repurposing them for precise genome editing. Our long-term goals are
to unravel the mechanisms underlying target nucleic acid recognition and cleavage mediated by diverse
CRISPR-Cas systems, which provide essential knowledge for safe and reliable use of this technology in
treating human diseases. In this proposal, we will work on the molecular mechanisms for four newly discovered
CRISRP-Cas systems, covering DNA targeting (Cas12i), RNA targeting (Cas12g) and CRISPR RNA guided
DNA transposition (VcCascade and Cas12k). As revealed in our structure, Cas12i accommodates longer
crRNA-DNA heteroduplex than currently used Cas effectors, thus potentially improve the specificity for genome
editing. The RNA-guided RNase Cas12g is compact and thermostable, and thus potentially expand the toolkits
for RNA editing and RNA-targeting applications. VcCascade and Cas12k direct transposition machinery for
RNA-guided DNA transposition, opening a new paradigm for genome editing independent of DNA repair
pathways.
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## Key facts

- **NIH application ID:** 10389613
- **Project number:** 3R01GM138675-02S1
- **Recipient organization:** PURDUE UNIVERSITY
- **Principal Investigator:** Leifu Chang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $98,922
- **Award type:** 3
- **Project period:** 2020-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10389613

## Citation

> US National Institutes of Health, RePORTER application 10389613, Molecular basis for CRISPR RNA-guided nucleic acid cleavage and DNA transposition (3R01GM138675-02S1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10389613. Licensed CC0.

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