Symmetry and Scale Orient Min Oscillation Patterns in Bacterial Shape Sculptures

Abstract

What are the effects of cellular confinement and cell shape on the intracellular organization, and vice versa? Here we present a novel nanostructuring technique to systematically ‘sculpt’ living bacterial cells into defined shapes, e.g. squares and rectangles, to explore the spatial adaptation of Min proteins that oscillate pole-to-pole to assist division-site selection at the mid-plane in rod-shape Escherichia coli.In a wide geometric parameter space, spanning cell volumes from 2x1x1 to 11x6x1 μm3, Min proteins are found to exhibit versatile oscillation patterns, sustaining rotational, longitudinal, diagonal, stripe, and even transversal modes. Their quantitative distributions reveal two essential properties that orient the Min patterns, viz., aligning to symmetry axes and a characteristic length range of 3-6 μm. Within this range, Min pattern are found to scale in adaptation to the cell length. The finding that Min patterns directly capture the symmetry and scale of the cell boundary to spatially regulate cell division refutes all previous geometry-sensing models that were based on the longest distance, membrane area or curvature.Using numerical simulations, we find that global symmetry selection and gradient scaling both derive from the local microscopic self-activation and inhibition kinetics, which are key components of the Turing reaction-diffusion mechanism underlying Min oscillatory dynamics. Both geometry-sensing properties only emerge within fully three-dimensionally confined volumes, contrasting in vitro Min waves on planes and theories with a fixed wavelength.Our results show that simple molecular interactions are capable of bridging the characteristics of cell shape to the spatiotemporal regulation of essential cellular processes.