Chromosome and replisome dynamics in E. coli: loss of sister cohesion triggers global chromosome movement and mediates chromosome segregation

Cell. 2005 Jun 17;121(6):899-911. doi: 10.1016/j.cell.2005.04.013.

Abstract

Chromosome and replisome dynamics were examined in synchronized E. coli cells undergoing a eukaryotic-like cell cycle. Sister chromosomes remain tightly colocalized for much of S phase and then separate, in a single coordinate transition. Origin and terminus regions behave differently, as functionally independent domains. During separation, sister loci move far apart and the nucleoid becomes bilobed. Origins and terminus regions also move. We infer that sisters are initially linked and that loss of cohesion triggers global chromosome reorganization. This reorganization creates the 2-fold symmetric, ter-in/ori-out conformation which, for E. coli, comprises sister segregation. Analogies with eukaryotic prometaphase suggest that this could be a primordial segregation mechanism to which microtubule-based processes were later added. We see no long-lived replication "factory"; replication initiation timing does not covary with cell mass, and we identify changes in nucleoid position and state that are tightly linked to cell division. We propose that cell division licenses the next round of replication initiation via these changes.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Chromosome Mapping
  • Chromosome Segregation*
  • Chromosomes, Bacterial / genetics*
  • Chromosomes, Bacterial / metabolism*
  • DNA Replication / physiology
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism*
  • Escherichia coli / genetics*
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism*
  • S Phase
  • Time Factors

Substances

  • Multienzyme Complexes
  • DNA synthesome
  • DNA-Directed DNA Polymerase