2026-02-10 カリフォルニア大学サンディエゴ校(UCSD)
Scientists have solved how circadian clocks within cyanobacteria, tiny organisms also known as blue-green algae, are able to precisely control when different genes are turned on and off during the 24-hour cycle.
<関連情報>
- https://today.ucsd.edu/story/researchers-rebuild-microscopic-circadian-clock-that-can-control-genes
- https://www.nature.com/articles/s41594-025-01740-0
シアノバクテリアにおける概日リズム転写のメカニズムと再構成 Mechanism and reconstitution of circadian transcription in cyanobacteria
Mingxu Fang,Yajie Gu,Miron Leanca,Mariusz Matyszewski,Andy LiWang,Yulia Yuzenkova,Kevin D. Corbett & Susan S. Golden
Nature Structural & Molecular Biology Published:10 February 2026
DOI:https://doi.org/10.1038/s41594-025-01740-0
Abstract
Circadian biological clocks evolved across kingdoms of life as an adaptation to predictable cycles of sunrise and sunset. In the cyanobacterium Synechococcus elongatus, a protein-based clock precisely controls when different genes are turned on and off during the 24-h day but the phasing mechanism remains unclear. Here we show the molecular basis of this regulation and reconstitute clock-controlled transcription in vitro using purified components. Biochemical and structural analyses revealed that the clock-regulated transcription factor RpaA can function as either an activator or a repressor of cyanobacterial RNA polymerase, depending on its binding position relative to core promoter elements. Leveraging the repressor mechanism, we developed a heterologous in vitro system driven by bacteriophage T7 RNA polymerase that sustains circadian transcription for multiple days. These findings explain how a single clock output generates opposite phases of gene expression and define the minimal components for circadian clock function, enabling synthetic or biotechnological applications.
