Protocol for enhancing Cas9 efficiency and fidelity through structure-guided phosphate-locking loop engineering.

Area of Science:

• Biochemistry
• Molecular Biology
• Gene Editing Technologies

Background:

• The phosphate-locking loop (PLL) is crucial for stabilizing Cas9-DNA interactions in CRISPR systems.
• Optimizing Cas9 efficiency and specificity is essential for advancing gene editing applications.
• Targeting the PLL offers a promising strategy for Cas9 enhancement.

Purpose of the Study:

• To present a protocol for structure-guided engineering of the Cas9 phosphate-locking loop (PLL).
• To enhance the efficiency and fidelity of Cas9 gene editing.
• To provide a generalizable framework for Cas9 ortholog engineering.

Main Methods:

• Sequence alignment and structural analysis to identify PLL engineering targets.
• Inverse PCR for constructing Cas9 variants with modified PLLs.
• Amplicon sequencing to evaluate gene editing efficiency.
• Genome-wide Unbiased Identification of DSBs Evaluated by sequencing (GUIDE-seq) to assess specificity.

Main Results:

• Demonstrated a protocol for structure-guided PLL engineering in Cas9.
• Successfully enhanced Cas9 efficiency and fidelity through PLL modifications.
• Validated the protocol's generalizability across different Cas9 orthologs.

Conclusions:

• Structure-guided engineering of the PLL is an effective strategy for improving Cas9 performance.
• The presented protocol offers a robust framework for developing enhanced Cas9 variants.
• This work facilitates the development of more precise and efficient gene editing tools.