Termination structures in the Escherichia coli chromosome replication fork trap

J Mol Biol. 2009 Apr 3;387(3):532-9. doi: 10.1016/j.jmb.2009.02.027. Epub 2009 Feb 20.


The Escherichia coli chromosome contains two opposed sets of unidirectional DNA replication pause (Ter) sites that, according to the replication fork trap theory, control the termination of chromosome replication by restricting replication fork fusion to the terminus region. In contrast, a recent hypothesis suggested that termination occurs at the dif locus instead. Using two-dimensional agarose gel electrophoresis, we examined DNA replication intermediates at the Ter sites and at dif in wild-type cells. Two definitive signatures of site-specific termination--specific replication fork arrest and converging replication forks--were clearly detected at Ter sites, but not at dif. We also detected a significant pause during the latter stages of replication fork convergence at Ter sites. Quantification of fork pausing at the Ter sites in both their native chromosomal context and the plasmid context further supported the fork trap model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Chromosomes, Bacterial* / chemistry
  • Chromosomes, Bacterial* / metabolism
  • DNA Replication*
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Molecular Sequence Data
  • Nucleic Acid Conformation*
  • Sequence Alignment
  • Terminator Regions, Genetic*


  • Escherichia coli Proteins