哥伦比亚大学Samuel H. Sternberg小组的最新研究探明了CRISPR-Cas12f同源物驱动RNA引导转录。相关论文于2026年3月4日发表于国际顶尖学术期刊《自然》杂志上。

本研究揭示了一种RNA引导的基因激活机制，涉及σ^E因子与核酸酶死亡Cas12f （dCas12f）复合物的协同作用。该研究团队在大肠杆菌主题RNA和染色质免疫沉淀实验中筛选了大量具有遗传连锁的dCas12f和σE同源物，揭示了具有最小5'-G靶标邻近基序的引导RNA富集和DNA靶标结合的系统。σ^E的募集依赖于dCas12f和引导RNA，提示蛋白与蛋白之间存在直接的相互作用，共表达实验表明，dCas12f-gRNA-σE三元配合物能够实现RNAP全酶的可编程募集。值得注意的是，dCas12f-RNA -σ^E复合物在没有任何必要的启动子基序的情况下驱动了有效的基因表达，而从头转录起始位点完全由与dcas12f介导的R环的相对距离决定。他们的发现突出了RNA引导转录的新范式，体现了让人想起CRISPR激活（CRISPRa）技术的自然特征。

研究人员表示，细菌转录起始是一个严格调控的过程，通常依赖于序列特异性启动子识别专用σ因子，导致RNA聚合酶（RNAP）的功能性DNA接合。虽然大肠杆菌中的7个σ因子已经被广泛表征，但拟杆菌门物种编码了数十个特殊的、胞质外功能σ因子（σ^E），其确切作用尚不清楚，这表明存在额外的调控潜力。

附：英文原文

Title: Exapted CRISPR–Cas12f homologues drive RNA-guided transcription

Author: Hoffmann, Florian T., Wiegand, Tanner, Palmieri, Adriana I., Glass-Klaiber, Juniper, Xiao, Renjian, Tang, Stephen, Le, Hoang C., Meers, Chance, Lampe, George D., Chang, Leifu, Sternberg, Samuel H.

Issue&Volume: 2026-03-04

Abstract: Bacterial transcription initiation is a tightly regulated process that canonically relies on sequence-specific promoter recognition by dedicated sigma (σ) factors, leading to functional DNA engagement by RNA polymerase (RNAP)1. Although the seven σ factors in Escherichia coli have been extensively characterized2, Bacteroidetes species encode dozens of specialized, extracytoplasmic function σ factors (σE) whose precise roles are unknown, pointing to additional layers of regulatory potential3. Here we uncover a mechanism of RNA-guided gene activation involving the coordinated action of σE factor in complex with nuclease-dead Cas12f (dCas12f). We screened a large set of genetically linked dCas12f and σE homologues in E. coli using RNA and chromatin immunoprecipitation experiments, revealing systems that exhibit robust guide RNA enrichment and DNA target binding with a minimal 5′-G target-adjacent motif. Recruitment of σE was dependent on dCas12f and guide RNA, suggesting direct protein–protein interactions, and co-expression experiments demonstrated that the dCas12f–gRNA–σE ternary complex was competent for programmable recruitment of the RNAP holoenzyme. Remarkably, dCas12f–RNA–σE complexes drove potent gene expression in the absence of any requisite promoter motifs, with de novo transcription start sites defined exclusively by the relative distance from the dCas12f-mediated R-loop. Our findings highlight a new paradigm of RNA-guided transcription that embodies natural features reminiscent of CRISPR activation (CRISPRa) technology4,5.

DOI: 10.1038/s41586-026-10166-7

Source: https://www.nature.com/articles/s41586-026-10166-7