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Non-linear Min protein interactions generate harmonics that signal mid-cell division in Escherichia coli
James C Walsh1,2, Christopher N Angstmann3, Iain G Duggin2
1School of Physics, University of New South Wales, Sydney, NSW, Australia.
Abstract:
The Min protein system creates a dynamic spatial pattern in Escherichia coli cells where the proteins MinD and MinE oscillate from pole to pole. MinD positions MinC, an inhibitor of FtsZ ring formation, contributing to the mid-cell localization of cell division. In this paper, Fourier analysis is used to decompose experimental and model MinD spatial distributions into time-dependent harmonic components. In both experiment and model, the second harmonic component is responsible for producing a mid-cell minimum in MinD concentration. The features of this harmonic are robust in both experiment and model. Fourier analysis reveals a close correspondence between the time-dependent behaviour of the harmonic components in the experimental data and model. Given this, each molecular species in the model was analysed individually. This analysis revealed that membrane-bound MinD dimer shows the mid-cell minimum with the highest contrast when averaged over time, carrying the strongest signal for positioning the cell division ring. This concurs with previous data showing that the MinD dimer binds to MinC inhibiting FtsZ ring formation. These results show that non-linear interactions of Min proteins are essential for producing the mid-cell positioning signal via the generation of second-order harmonic components in the time-dependent spatial protein distribution.
Insights
The Min protein system uses dynamic oscillations to ensure bacterial cell division occurs at the cell
Area of Science:
- Cell Biology
- Microbiology
- Biophysics
Background:
- The Min protein system in Escherichia coli regulates cell division placement.
- MinD and MinE proteins oscillate pole-to-pole, influencing cell division site.
- MinD interacts with MinC to inhibit FtsZ ring formation at cell poles.
Purpose of the Study:
- To analyze the spatial distribution of MinD protein using Fourier analysis.
- To understand the role of harmonic components in MinD localization.
- To identify the molecular species responsible for the mid-cell division signal.
Main Methods:
- Fourier analysis applied to experimental and model-based MinD spatial distributions.
- Decomposition of protein distributions into time-dependent harmonic components.
- Individual analysis of molecular species within the computational model.
Main Results:
- The second harmonic component of MinD distribution is crucial for mid-cell minimum.
- Experimental and model data show strong correspondence in harmonic component behavior.
- Membrane-bound MinD dimer exhibits the highest contrast mid-cell minimum signal.
Conclusions:
- Non-linear interactions within the Min system generate essential harmonic components.
- The MinD dimer-MinC complex provides the primary signal for cell division positioning.
- Fourier analysis effectively characterizes the dynamic spatial regulation of bacterial cytokinesis.