"Physical considerations in the birth and death of messenger RNAs in vivo"
The flow of genetic information from DNA to messenger RNA and to protein is one of the fundamental processes in biology. RNA polymerase is a molecular motor that is in charge of the first step of this process, i.e. transcription of DNA into mRNAs. Inside cells, multiple copies of RNA polymerases translocate along the same DNA template concurrently, and whether they exhibit any group dynamics, similar to other well-known molecular motors, remains unclear. Using single-molecule mRNA imaging from fixed bacterial cells, we measured the relationship between the density of RNA polymerases and their speed, and our results support long-distance cooperation between the polymerases. Surprisingly, we found that the cooperation can turn into antagonism when the promoter is turned off. Our model suggests that these two contrasting modes of transcription are mediated by the mechanical stress associated with DNA supercoiling. In the second part of my talk, I will present our recent study on mRNA degradation. Using single-particle tracking, we measured the diffusion dynamics of the mRNA degradation enzymes in bacteria, and we analyzed how subcellular localization and mobility of the enzymes affect mRNA degradation kinetics.
