Cell Boundary Confinement Sets the Size and Position of the E. coli Chromosome

Cell Boundary Confinement Sets the Size and Position of the E. coli Chromosome

Wu, Fabai (Kavli institute of nanoscience Delft; California Institute of Technology; Student TU Delft)
Swain, Pinaki (Indian Institute of Technology Hyderabad)
Kuijpers, L.C. (TU Delft BN/Nynke Dekker Lab; Kavli institute of nanoscience Delft)
Zheng, X.Z. (TU Delft BN/Sander Tans Lab; Kavli institute of nanoscience Delft)
Felter, K.M. (TU Delft ChemE/Opto-electronic Materials; Kavli institute of nanoscience Delft)
Guurink, M. (Kavli institute of nanoscience Delft; Student TU Delft)
Solari, Jacopo (AMOLF)
Jun, Suckjoon (University of California)
Dekker, C. (TU Delft BN/Cees Dekker Lab; Kavli institute of nanoscience Delft)

2019

Although the spatiotemporal structure of the genome is crucial to its biological function, many basic questions remain unanswered on the morphology and segregation of chromosomes. Here, we experimentally show in Escherichia coli that spatial confinement plays a dominant role in determining both the chromosome size and position. In non-dividing cells with lengths increased to 10 times normal, single chromosomes are observed to expand > 4-fold in size. Chromosomes show pronounced internal dynamics but exhibit a robust positioning where single nucleoids reside robustly at mid-cell, whereas two nucleoids self-organize at 1/4 and 3/4 positions. The cell-size-dependent expansion of the nucleoid is only modestly influenced by deletions of nucleoid-associated proteins, whereas osmotic manipulation experiments reveal a prominent role of molecular crowding. Molecular dynamics simulations with model chromosomes and crowders recapitulate the observed phenomena and highlight the role of entropic effects caused by confinement and molecular crowding in the spatial organization of the chromosome. Imaging chromosomes in E. coli within a broad length range, Wu et al. observe that chromosome size and position strongly depend on cell size. They provide evidence that this arises from a confinement-modulated entropic repulsion between chromosome and cytosolic crowders, highlighting the importance of confinement effects in cellular organization.

bacterial nucleoid
cell boundary confinement
chromosome segregation
chromosome size
crowders

http://resolver.tudelft.nl/uuid:facbd3b6-eb86-4bb8-86f5-a57767f76826

https://doi.org/10.1016/j.cub.2019.05.015

2020-07-08

0960-9822

Current Biology, 29 (13), 2131-2144.e4

Institutional Repository

journal article

© 2019 Fabai Wu, Pinaki Swain, L.C. Kuijpers, X.Z. Zheng, K.M. Felter, M. Guurink, Jacopo Solari, Suckjoon Jun, C. Dekker, More Authors