Stochastic variation and regulation of bacterial DNA repair and mutagenesis (360G-Wellcome-206159_Z_17_B)

Studying the molecular mechanisms of mutagenesis is crucial to understanding genome evolution and the emergence of drug resistance in pathogens. It is known that cellular stress responses increase mutation rates after DNA damage and antimicrobial treatment. Recent evidence suggests that stochastic effects play key roles in these responses, causing cell-to-cell variation in mutation rates and diversifying cell phenotypes to evade drug treatment. However, existing cell biology, biochemistry, and genetics assays fail to resolve mutation rate dynamics and cellular heterogeneity. By combining live-cell single-molecule microscopy, single-cell manipulation, and DNA sequencing techniques, I will bridge the divide between molecular-level and genome-level approaches. I will visualise mutagenic molecular processes in real-time and link them to genome sequence changes in individual bacterial cells. Ultimately, I will discover how individual mutation events are related to single-cell phenotypes such as DNA repair activities, stress responses, and growth characteristics. My focus will be on the conserved SOS response that globally regulates genome maintenance and has been implicated in the bacterial response to antibiotics. Using a novel method to quantify post-translational modifications of the master SOS regulator, I will uncover the molecular choreography of the SOS response and establish how it contributes to the evolution of antibiotic resistance.