title: A defined terminal region of the E. coli chromosome shows late segregation and high FtsK activity.
abstract: BACKGROUND
  The FtsK DNA-translocase controls the last steps of chromosome segregation in E. coli. It translocates sister chromosomes using the KOPS DNA motifs to orient its activity, and controls the resolution of dimeric forms of sister chromosomes by XerCD-mediated recombination at the dif site and their decatenation by TopoIV.
  
  
  METHODS
  We have used XerCD/dif recombination as a genetic trap to probe the interaction of FtsK with loci located in different regions of the chromosome. This assay revealed that the activity of FtsK is restricted to a ∼400 kb terminal region of the chromosome around the natural position of the dif site. Preferential interaction with this region required the tethering of FtsK to the division septum via its N-terminal domain as well as its translocation activity. However, the KOPS-recognition activity of FtsK was not required. Displacement of replication termination outside the FtsK high activity region had no effect on FtsK activity and deletion of a part of this region was not compensated by its extension to neighbouring regions. By observing the fate of fluorescent-tagged loci of the ter region, we found that segregation of the FtsK high activity region is delayed compared to that of its adjacent regions.
  
  
  CONCLUSIONS
  Our results show that a restricted terminal region of the chromosome is specifically dedicated to the last steps of chromosome segregation and to their coupling with cell division by FtsK.
authors.affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Deghorain
authors.forename: Carine
authors.initials: C
authors.lastname: Pagès
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Meile
authors.forename: Mathieu
authors.initials: M
authors.lastname: Stouf
authors.forename: Hervé
authors.initials: H
authors.lastname: Capiaux
authors.forename: Romain
authors.initials: R
authors.lastname: Mercier
authors.forename: Christian
authors.initials: C
authors.lastname: Lesterlin
authors.forename: Bernard
authors.initials: B
authors.lastname: Hallet
authors.forename: François
authors.initials: F
authors.lastname: Cornet
mesh_terms: D020090:Chromosome Segregation; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D048168:Escherichia coli K12 / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D059372:Nucleotide Motifs; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins