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St. Jude Screen Rapidly Optimizes CAST Editors With Higher Precision and Activity

The peer-reviewed study introduces a scalable assay that profiles thousands of RNA-guided transposon variants to guide engineering.

Overview

  • The method measures both insertion efficiency and on-target specificity in a single high-throughput experiment.
  • The team focused on the V-K CAST subtype and systematically screened a library covering every possible single-point mutation.
  • Combining select beneficial mutations increased activity about fivefold while preserving or improving specificity.
  • The work, published September 23, 2025 in Nucleic Acids Research, offers mechanistic insight and a platform for iterative design.
  • Researchers note that CASTs can integrate large DNA payloads but underperform in human cells, so translation beyond bacterial systems remains a next step.