A quantitative model for the dynamics of target recognition and off-target rejection by the CRISPR-Cas Cascade

Marius Rutkauskas1, Inga Songailiene2, Patrick Irmisch1

  • 1Peter Debye Institute for Soft Matter Physics, Universität Leipzig, 04103, Leipzig, Germany.

Nature Communications
|December 2, 2022
PubMed

Insights

CRISPR-Cas genome engineering relies on precise target recognition. This study models off-target DNA binding dynamics, revealing DNA supercoiling controls target recognition initiation, crucial for improving CRISPR-Cas specificity.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biophysics

Background:

  • CRISPR-Cas systems are powerful genome engineering tools relying on crRNA-guided DNA targeting.
  • Off-target recognition, due to partial complementarity, limits CRISPR-Cas precision and lacks predictive models.
  • Understanding target recognition dynamics is key to mitigating off-target effects.

Purpose of the Study:

  • To quantitatively analyze the target recognition dynamics of the CRISPR-Cas Cascade complex on mismatched DNA targets.
  • To develop a predictive model for CRISPR-Cas off-target recognition.
  • To elucidate the factors controlling the initiation of target recognition.

Main Methods:

  • Utilized single-molecule supercoiling experiments to study Cascade complex interactions with various DNA targets.
  • Developed a quantitative model based on a random walk mechanism to describe target recognition dynamics.
  • Analyzed recognition of targets with single and double mutations, including positional effects.

Main Results:

  • Demonstrated that target recognition dynamics can be modeled as a random walk along the crRNA-DNA hybrid.
  • The model accurately predicts recognition of targets with single and double mutations, accounting for mutation position and proximity.
  • Identified DNA supercoiling, not the Cascade structure, as the primary controller of the seed length for target recognition initiation.

Conclusions:

  • The developed random walk model provides a quantitative basis for predicting CRISPR-Cas off-target effects.
  • Understanding the role of DNA supercoiling in target recognition is critical for enhancing CRISPR-Cas specificity.
  • This work advances the predictive power and precision of genome engineering technologies.

Related Concept Videos

CRISPR01:59

CRISPR

Genome editing technologies allow scientists to modify an organism’s DNA via the addition, removal, or rearrangement of genetic material at specific genomic locations. These types of techniques could potentially be used to cure genetic disorders such as hemophilia and sickle cell anemia. One popular and widely used DNA-editing research tool that could lead to safe and effective cures for genetic disorders is the CRISPR-Cas9 system. CRISPR-Cas9 stands for Clustered Regularly Interspaced...
52.7K
The Antiviral System of Bacteria and Archaea: CRISPR01:23

The Antiviral System of Bacteria and Archaea: CRISPR

CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats is a adaptive immune system found in bacteria and archaea that protects against viral infections. This system enables prokaryotic cells to identify, remember, and neutralize foreign genetic elements, primarily bacteriophages, by storing fragments of the invader’s DNA as a genetic memory.The CRISPR immune response begins during an initial infection. Cas (CRISPR-associated) proteins play a central role in this...
89
CRISPR and crRNAs02:53

CRISPR and crRNAs

Bacteria and archaea are susceptible to viral infections just like eukaryotes; therefore, they have developed a unique adaptive immune system to protect themselves. Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR-Cas) are present in more than 45% of known bacteria and 90% of known archaea.
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
17.3K
CRISPR/Cas9 Genome Editing01:28

CRISPR/Cas9 Genome Editing

The CRISPR-Cas system serves as a bacterial defense mechanism against invading genetic elements such as viruses and plasmids, forming the foundation for its adaptation as a powerful genome-editing tool. Originally discovered in prokaryotes, this system has been repurposed to revolutionize genetic engineering across a wide range of organisms, including plants, animals, and humans. The core component, Cas9, is an endonuclease derived from Streptococcus pyogenes, capable of introducing...
132