Increasing the specificity of CRISPR systems with engineered RNA secondary structures

Area of Science:

• Molecular Biology
• Gene Editing Technologies
• Biotechnology

Background:

• CRISPR systems are widely used in research and therapy.
• Off-target activity of CRISPR nucleases poses risks for applications.
• Improving CRISPR specificity is crucial for safety and accuracy.

Purpose of the Study:

• To investigate methods for enhancing CRISPR specificity.
• To assess the impact of engineered RNA secondary structures on nuclease activity.
• To develop more precise gene editing tools.

Main Methods:

• Engineered single-guide RNAs with hairpin secondary structures (hp-sgRNAs).
• Tested hp-sgRNAs with Streptococcus pyogenes Cas9 (SpCas9) transactivator.
• Evaluated hp-sgRNAs with five different Cas9 and Cas12a variants for gene editing specificity.

Main Results:

• Designed hp-sgRNAs increased specificity by several orders of magnitude.
• hp-sgRNAs successfully tuned the activity of SpCas9 transactivator.
• Enhanced specificity was observed across multiple Cas9 and Cas12a variants.

Conclusions:

• RNA secondary structure is a key factor in tuning CRISPR effector activity.
• hp-sgRNAs represent a significant advancement in improving CRISPR specificity.
• This strategy offers a versatile approach to enhance precision in gene editing.