Synergistic HMGN1 and VP64 Fusions Potentiate High‐Precision and PAM‐Flexible Base Editing

Jun 11, 2026Advanced science (Weinheim, Baden-Wurttemberg, Germany)

Combined HMGN1 and VP64 proteins improve precise and flexible base editing

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CRISPR Gene Editing on OpenScience ↗PubMed ↗DOI ↗OA ↗

Abstract

The new base editors achieved enhanced editing efficiency in yeast and rice without significantly increasing off-target effects.

A combination of SpRY and truncated CDA1 cytidine deaminases allows for precise editing of nearly any cytosine in the genome.
Initial efficiency of this combination was suboptimal, prompting screening of various DNA-binding proteins.
The fusion of HMGN1 and VP64 significantly improved editing activity while maintaining precision.
The new base editors may have broad applicability in gene therapy, precision breeding, and fundamental research.

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RNA-guided CRISPR-derived base editors (BEs) have revolutionized genome editing by enabling targeted base substitutions. However, their application is frequently constrained by the stringent requirement for PAM sequences and low editing precision (bystander editing). Here, we present a robust strategy to overcome these limitations by coupling SpRY, a near-PAM-less Cas9 variant, with truncated CDA1 cytidine deaminases. While this combination enables precise editing of virtually any cytosine in the genome, it initially exhibited suboptimal efficiency. To address this, we systematically screened a diverse panel of candidate DNA-binding proteins and identified that the synergistic fusion of HMGN1 and VP64 substantially enhances editing activity without compromising precision. Importantly, this enhanced editing efficiency was achieved without markedly increasing off-target effects. Our new BEs demonstrated robust performance not only in yeast but also in rice, suggesting broad applicability in gene therapy, precision breeding, and fundamental research.