Speed fluctuations of bacterial replisomes

Abstract

Replisomes are multi-protein complexes that replicate genomes with remarkable speed and accuracy. Despite their importance, the dynamics of replisomes along the genome is poorly characterised, especially in vivo. In this paper, we link the replisome dynamics with the DNA abundance distribution measured in an exponentially growing bacterial population. Our approach permits to accurately infer the replisome dynamics along the genome from deep sequencing measurements. As an application, we experimentally measured the DNA abundance distribution in Escherichia coli populations growing at different temperatures. We find that the average replisome speed increases nearly five-fold between 17°C and 37°C. Further, we observe wave-like variations of the replisome speed along the genome. These variations are correlated with previously observed variations of the mutation rate along the genome. We interpret this correlation as a speed– error trade-off and discuss its possible dynamical origin. Our approach has the potential to elucidate replication dynamics in E. coli mutants and in other bacterial species.