CRISPR-Cas9 conformational activation as elucidated from enhanced molecular simulations

Area of Science:

• Biophysics
• Molecular Biology
• Genomics

Background:

• CRISPR-Cas9 is a powerful genome editing tool.
• The precise structural and mechanistic details of Cas9 function remain largely unknown.

Purpose of the Study:

• To elucidate the conformational dynamics of the Cas9 enzyme during its activation and catalysis.
• To provide atomic-level insights into the CRISPR-Cas9 mechanism for future research and tool development.

Main Methods:

• Extensive molecular simulations using Gaussian-accelerated molecular dynamics (GaMD).
• Probing conformational changes over microsecond to millisecond timescales.

Main Results:

• Revealed the conformational transition of Cas9 from apo to RNA-bound states, suggesting an RNA recruitment mechanism.
• Identified the catalytically competent Cas9 conformation.
• Demonstrated that DNA binding induces conformational changes in the HNH domain, leading to the active state for DNA cleavage.

Conclusions:

• The study provides a detailed atomic-level understanding of the CRISPR-Cas9 molecular mechanism.
• Findings offer insights into RNA recruitment and DNA cleavage regulation.
• Results will guide future experimental studies and the development of novel CRISPR-Cas9-based tools.