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Suckjoon JunWe are interested in the underlying mechanism of chromosome and plasmid segregation in bacteria and its evolution. Our recent theoretical studies have shown that polymers in strong confinement, such as chromosomes in bacteria, can partition spontaneously to maximize their conformational entropy. This is a strong indication that, with or without protein-based “mitotic machinery,” conformational entropy provides a primordial driving force of segregation for duplicating bacterial chromosomes. In particular, very recently, we have completed a phase diagram of two-chain polymer solution in a rectangular box of arbitrary aspect ratio. Our phase diagram indeed predicts entropy-driven chromosome segregation in rod-shaped bacteria, whereas plasmids, because of their small sizes, can readily mix one another. This suggests that the active segregation mechanism of most low-copy number plasmids (such as R1) might be a product of evolutionary selection. Indeed, the main goal of our research at the Center is to study, both theoretically and experimentally, the role of basic physical principles on the fitness and viability of bacteria in the context of chromosome segregation. For our experimental approach, briefly, we plan to construct an “artificial cell” environment by combining microfluidics and single-molecule manipulation techniques, using which we are hoping to measure the physical forces and dynamics of isolated nucleoids in microchannels. ContactJun lab |
