Nucleic Acid-Dependent Conformational Changes in CRISPR-Cas9 Revealed by Site-Directed Spin Labeling

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• The CRISPR-Cas9 system is a powerful tool for genome engineering.
• Understanding the conformational changes in Cas9 is crucial for elucidating its mechanism of action.
• Previous studies suggest RNA and DNA binding induce conformational shifts in Cas9.

Purpose of the Study:

• To investigate nucleic acid-dependent conformational changes in Streptococcus pyogenes Cas9 (SpyCas9).
• To utilize site-directed spin labeling (SDSL) to monitor these dynamic changes.
• To provide insights into the functional mechanism of the CRISPR-Cas9 system.

Main Methods:

• Site-directed spin labeling (SDSL) was employed on SpyCas9.
• Single nitroxide spin labels were attached to native cysteine residues (Cys80 and Cys574).
• Electron paramagnetic resonance (EPR) spectroscopy was used to analyze conformational changes.

Main Results:

• Spin-labeled SpyCas9 retained its biological function.
• EPR spectra indicated large-scale domain rearrangements in SpyCas9 upon RNA binding.
• Conformational changes were observed at Cys80, linked to RNA interaction.

Conclusions:

• SDSL is an effective method for monitoring conformational dynamics in CRISPR-Cas9.
• RNA binding induces significant structural rearrangements in SpyCas9.
• This research provides key information for understanding the CRISPR-Cas9 mechanism.