Biophysical Society Thematic Meeting| Lima 2019

Revisiting the Central Dogma of Molecular Biology at the Single-Molecule Level

Poster Abstracts

7-POS Board 7 GEOMETRIC CUES OF BACTERIA CELL-DIVISION REGULATING PROTEINS REVEALED THROUGH MICROFLUIDIC CONFINEMENT Chia-Fu Chou 1 ; Jie-Pan Shen 1,3 ; Yi-Ren Chang 2 ; 1 Academia Sinica, Institute of Physics, Taipei, Taiwan 2 National Taiwan Normal University, Department of Physics, Taipei, Taiwan 3 National Tsing Hua University, Dept. Engineering and System Sciences, Hsinchu, Taiwan Dynamic pattern formations are often encountered in biological systems, constrained by boundary conditions imposed by cell geometry, such as eukaryotic polar differentiation in embryonic development. In many Proteobacteria, septum positioning at mid-cell is ascribed to the sensing capability of the cell-division regulating Min proteins, which undergo dynamic pole- to-pole oscillations. It is currently uncertain whether these oscillations are driven by curvature- mediated localization of MinD around membranes with high negative curvature (diffusion-and- capture hypothesis, or DCH) or whether geometric boundaries imposed by membrane patches determine the reaction-diffusion propagation axis of the Min proteins. To explore the geometric cues behind the distribution of Min proteins during its oscillation, we use microfluidic confinement to gently reshape round mutants of the rod-shaped bacterium Escherichia coli, which reveals a dominant distribution of MinD around positively curved regions of the cell periphery, in sharp contrast to DCH. We then construct a phenomenological formalism based on the principle of wave spreading and the permissive modes of chemical waves indicating that the global membrane geometry, rather than the local curvature, is the primary cue for the localization of membrane-bound MinD, a finding well supported by our experimental observations. Our study suggests a framework for quantitative analysis extendable to other wave-like biopatterning systems without solving the reaction-diffusion equations.

43