Impact of crowders on the morphology of bacterial chromosomes

TL;DR

This study investigates how cytosolic crowders influence bacterial chromosome morphology, revealing spontaneous helicity and segregation transitions through experimental inspiration and simplified modeling.

Contribution

It introduces a novel 'feather-boa' model to explain crowder effects on chromosome structure and demonstrates spatial segregation transitions.

Findings

Spontaneous emergence of helicity in chromosome and crowders

Segregation transitions depend on crowder size

Effective models replicate experimental observations

Abstract

Inspired by recent experiments on the effects of cytosolic crowders on the organization of bacterial chromosomes, we consider a "feather-boa" type model chromosome in the presence of non-additive crowders, encapsulated within a cylindrical cell. We observe spontaneous emergence of complementary helicity of the confined polymer and crowders. This feature is reproduced within a simplified effective model of the chromosome. This latter model further establishes the occurrence of longitudinal and transverse spatial segregation transitions between the chromosome and crowders upon increasing crowder size.