Deriving biological principles from replication initiation control in bacteria

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The project aims to elucidate how bacterial cells decide when to start DNA replication, and also disseminate key single-cell technologies used in the research. While DNA replication is one of the most precise processes underlying cellular reproduction, how cells maintain the precision under different growth conditions has remained unsolved for over 50 years despite extensive studies. To this end, the project brings together tools and ways of thinking from multiple disciplines, including single-cell technologies that allow continuous tracking of a large number of individual cells. These technologies were originally invented in the PI’s laboratory, and have been streamlined over the years so that even undergraduate students can perform original research alongside graduate students and postdoctoral researchers. In the proposed activities, undergraduate students from underrepresented minority groups will disseminate the single- cell technologies to the broad scientific community using modern knowledge dissemination platforms, so that a typical biological lab can implement the same approaches practically at no cost. Some of the key experiments, once completed, will be integrated into the design of a biological physics laboratory course that the PI will develop.The research program will focus on DnaA, a widely conserved master regulator of replication initiation in bacteria. Based on how cell size at initiation responds to various growth conditions, a quantitative model is proposed to explain how production of DnaA and their biochemical properties robustly control the initiation process in a physiology-independent manner. The predictions of the model will be tested by using genetic mutants of DnaA and associated proteins, as well as precision measurements of various single-cell parameters using state-of-the-art microfluidics and imaging methods. The final output of this research will provide a mechanistic insight into the precision control of DNA replication initiation generalizable to a wide range of physiological conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.