Bistable protein distributions in rod-shaped bacteria

TL;DR

This paper investigates how protein distributions in rod-shaped bacteria form and fluctuate, revealing that cell length and protein number significantly influence the stability of polar protein assemblies.

Contribution

It introduces a generic model for spontaneous polar protein assembly based on cooperative membrane binding, analyzing how noise affects pattern stability.

Findings

Switching time between poles increases exponentially with cell length.

Switching time also increases with protein number.

Protein distribution patterns are highly sensitive to molecular noise.

Abstract

The distributions of many proteins in rod-shaped bacteria are far from homogenous. Often they accumulate at the cell poles or in the cell center. At the same time, the copy number of proteins in a single cell is relatively small making the patterns noisy. To explore limits to protein patterns due to molecular noise, we studied a generic mechanism for spontaneous polar protein assemblies in rod-shaped bacteria, which is based on cooperative binding of proteins to the cytoplasmic membrane. For mono-polar assemblies, we find that the switching time between the two poles increases exponentially with the cell length and with the protein number.