Kinetics of large-scale chromosomal movement during asymmetric cell division in Escherichia coli

PLoS Genet. 2017 Feb 24;13(2):e1006638. doi: 10.1371/journal.pgen.1006638. eCollection 2017 Feb.

Abstract

Coordination between cell division and chromosome replication is essential for a cell to produce viable progeny. In the commonly accepted view, Escherichia coli realize this coordination via the accurate positioning of its cell division apparatus relative to the nucleoids. However, E. coli lacking proper positioning of its cell division planes can still successfully propagate. Here, we characterize how these cells partition their chromosomes into daughters during such asymmetric divisions. Using quantitative time-lapse imaging, we show that DNA translocase, FtsK, can pump as much as 80% (3.7 Mb) of the chromosome between daughters at an average rate of 1700±800 bp/s. Pauses in DNA translocation are rare, and in no occasions did we observe reversals at experimental time scales of a few minutes. The majority of DNA movement occurs at the latest stages of cell division when the cell division protein ZipA has already dissociated from the septum, and the septum has closed to a narrow channel with a diameter much smaller than the resolution limit of the microscope (~250 nm). Our data suggest that the narrow constriction is necessary for effective translocation of DNA by FtsK.

MeSH terms

  • Asymmetric Cell Division / genetics*
  • Chromosomes, Bacterial / genetics*
  • Chromosomes, Bacterial / metabolism
  • DNA, Bacterial / genetics*
  • DNA, Bacterial / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Kinetics
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Microscopy, Fluorescence
  • Models, Genetic
  • Time-Lapse Imaging / methods

Substances

  • DNA, Bacterial
  • Escherichia coli Proteins
  • FtsK protein, E coli
  • Luminescent Proteins
  • Membrane Proteins

Grants and funding

This work was supported in part by University of Tennessee start-up funds and the National Science Foundation grant number MCB-1252890. Part of this research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.