Circadian Clock Coordinates Spatial Distributions of RNAP and Ribosome in Cyanobacteria

Abstract

The spatiotemporal distribution of cellular macromolecules is crucial for gene expression in prokaryotes note for open-plan layout cytoplasm. By fluorescent labeling, we visualized the spatiotemporal dynamics of RNA polymerase (RNAP) and ribosome in a model cyanobacterium for circadian research (Synechococcus elongatus PCC 7942). Similar to the nucleoids, both RNAPs and ribosomes showed circadian subcellular distributions. The RNAPs always colocalized with the chromosome during the oscillating diffused/compacted states, while the circadian distribution of the ribosomes displayed a dynamic pattern with the coincident/segregated states. Rifampicin and chloramphenicol treatment suggested RNAPs localization mainly depended on nucleoid exclusion while ribosome localization was a combined effect of nucleoid exclusion and RNA/protein synthesis. The spatiotemporal distributions of RNAPs and ribosomes were not susceptible to environmental factors and cell division but required the key clock protein KaiC. The results indicate spatiotemporal distributions of the central dogma are driven by the circadian clock in cyanobacteria.