9N9O

Cryo-EM structure of the dCas12f-gRNA-dsDNA complex (full R-Loop)

9N9O の概要

• エントリーDOI: 10.2210/pdb9n9o/pdb
• EMDBエントリー: 49174
• 分子名称: Nuclease-deactivated Cas12f, DNA non-template strand, DNA template strand, ... (4 entities in total)
• 機能のキーワード: dcas12f, full r-loop, rna binding protein, rna binding protein-dna-rna complex, rna binding protein/dna/rna
• 由来する生物種: Flagellimonas taeanensis; 詳細
• タンパク質・核酸の鎖数: 5
• 化学式量合計: 152730.03

構造登録者

Chang, L.,Sternberg, S.H.,Xiao, R.,Hoffmann, F.T.,Wiegand, T.,Xie, D. (登録日: 2025-02-11, 公開日: 2025-12-24, 最終更新日: 2026-03-18)

主引用文献

Xiao, R.,Hoffmann, F.T.,Xie, D.,Wiegand, T.,Palmieri, A.I.,Sternberg, S.H.,Chang, L.
Structural basis of RNA-guided transcription by a dCas12f-sigma E -RNAP complex.
Nature, 2026

PubMed Abstract: In both natural and engineered biological systems, RNA-guided proteins have emerged as critical transcriptional regulators by modulating RNA polymerase (RNAP) and its associated factors. In bacteria, diverse clades of repurposed TnpB and CRISPR-associated proteins repress gene expression by blocking transcription initiation or elongation, enabling non-canonical modes of regulatory control and adaptive immunity. A distinct class of nuclease-dead Cas12f homologues (dCas12f) instead activates gene expression through its association with unique extracytoplasmic function sigma factors (σ), although the molecular basis has remained elusive. Here we reveal a new mode of RNA-guided transcription initiation by determining the cryo-electron microscopy structures of the dCas12f-σ system from Flagellimonas taeanensis. We captured multiple conformational and compositional states, including the DNA-bound dCas12f-σ-RNAP holoenzyme complex, revealing how RNA-guided DNA binding leads to σ-RNAP recruitment and nascent mRNA synthesis at a precisely defined distance downstream of the R-loop. Rather than following the classical paradigm of σ-dependent promoter recognition, these studies show that recognition of the -35 element is largely supplanted by CRISPR-Cas targeting, whereas the melted -10 element is stabilized through unusual stacking interactions rather than insertion into the typical recognition pocket. Collectively, this work provides high-resolution insights into an unexpected mechanism of RNA-guided transcription, expanding our understanding of bacterial gene regulation and opening new avenues for programmable transcriptional control.

PubMed: 41781609
DOI: 10.1038/s41586-026-10178-3

実験手法

ELECTRON MICROSCOPY (3.42 Å)