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<p>The search for target sites on chromatin by eukaryotic sequence-specific transcription factors (TFs) is integral to the regulation of gene expression but the mechanism of nuclear exploration has remained obscure. Here we use multicolor single-molecule fluorescence resonance energy transfer and single-particle imaging to track the diffusion of purified <i>Drosophila</i> GAGA factor (GAF) on DNA and nucleosomes. Monomeric GAF DNA-binding domain (DBD) bearing one zinc finger finds its cognate site through one-dimensional (1D) or three-dimensional (3D) diffusion on bare DNA and rapidly slides back and forth between naturally clustered motifs for seconds before dissociation. Multimeric, full-length GAF also finds clustered motifs on DNA through 1D–3D diffusion but remains locked on target for longer periods. Nucleosome architecture effectively blocks GAF-DBD 1D sliding into the histone core but favors retention of GAF-DBD once it has bound to a solvent-exposed motif through 3D diffusion. Despite the occlusive nature of nucleosomes, 1D–3D facilitated diffusion enables GAF to effectively search for clustered cognate motifs in chromatin, providing a mechanism for navigation to nucleosomal and nucleosome-free sites by a member of the zinc finger TF family.</p>

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GAGA zinc finger transcription factor searches chromatin by 1D–3D facilitated diffusion

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月5日

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  • Xinyu A. Feng,
  • Maryam Yamadi,
  • Yiben Fu,
  • Kaitlin M. Ness,
  • Celina Liu,
  • Ishtiyaq Ahmed,
  • Gregory D. Bowman,
  • Margaret E. Johnson,
  • Taekjip Ha,
  • Carl Wu

摘要

The search for target sites on chromatin by eukaryotic sequence-specific transcription factors (TFs) is integral to the regulation of gene expression but the mechanism of nuclear exploration has remained obscure. Here we use multicolor single-molecule fluorescence resonance energy transfer and single-particle imaging to track the diffusion of purified Drosophila GAGA factor (GAF) on DNA and nucleosomes. Monomeric GAF DNA-binding domain (DBD) bearing one zinc finger finds its cognate site through one-dimensional (1D) or three-dimensional (3D) diffusion on bare DNA and rapidly slides back and forth between naturally clustered motifs for seconds before dissociation. Multimeric, full-length GAF also finds clustered motifs on DNA through 1D–3D diffusion but remains locked on target for longer periods. Nucleosome architecture effectively blocks GAF-DBD 1D sliding into the histone core but favors retention of GAF-DBD once it has bound to a solvent-exposed motif through 3D diffusion. Despite the occlusive nature of nucleosomes, 1D–3D facilitated diffusion enables GAF to effectively search for clustered cognate motifs in chromatin, providing a mechanism for navigation to nucleosomal and nucleosome-free sites by a member of the zinc finger TF family.