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A defined terminal region of the E. coli chromosome shows late segregation and high FtsK activity.

Deghorain M, Pagès C, Meile JC, Stouf M, Capiaux H, Mercier R, Lesterlin C, Hallet B, Cornet F - PLoS ONE (2011)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France.

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.

Methodology: 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.

Significance: 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.

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Related in: MedlinePlus

Preferential interaction with the FtsK high activity region requires all domains of FtsK.Same legend as Figure 2. The grey curve corresponds to ftsKwt strains and is redrawn from figure 2. Recombination frequencies were measured at chosen loci in different ftsK mutant: Green dots: ftsKATP-; blue dots: Δ(ftsKγ); red dots Δ(ftsKLC) strains producing FtsKC from plasmid pFX150 (Materials and methods). The yellow zone indicates extend of the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).
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pone-0022164-g003: Preferential interaction with the FtsK high activity region requires all domains of FtsK.Same legend as Figure 2. The grey curve corresponds to ftsKwt strains and is redrawn from figure 2. Recombination frequencies were measured at chosen loci in different ftsK mutant: Green dots: ftsKATP-; blue dots: Δ(ftsKγ); red dots Δ(ftsKLC) strains producing FtsKC from plasmid pFX150 (Materials and methods). The yellow zone indicates extend of the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).

Mentions: To investigate which features of FtsK are required for its preferential interaction with the FtsK high activity region, we first produced FtsKC detached from FtsKN from plasmid pFX150 in Δ(ftsKLC) strains (Materials and Methods). Production of FtsKC was induced using 0.03% arabinose, which yields a low but detectable level of protein [19]. As expected, this resulted in high recombination frequencies (red dots in Figure 3). Importantly, recombination frequencies were equivalent at all loci assayed (Figure 3). These results show that FtsKC can interact with the different chromosome regions at equivalent frequencies when unlinked from the division septum. It also follows that the XerCD recombinases have equal access to dif sites inserted into the different chromosome regions. We infer from these data that the restriction of FtsK activity to the FtsK high activity region depends on the tethering of FtsK to the division septum by FtsKN.


A defined terminal region of the E. coli chromosome shows late segregation and high FtsK activity.

Deghorain M, Pagès C, Meile JC, Stouf M, Capiaux H, Mercier R, Lesterlin C, Hallet B, Cornet F - PLoS ONE (2011)

Preferential interaction with the FtsK high activity region requires all domains of FtsK.Same legend as Figure 2. The grey curve corresponds to ftsKwt strains and is redrawn from figure 2. Recombination frequencies were measured at chosen loci in different ftsK mutant: Green dots: ftsKATP-; blue dots: Δ(ftsKγ); red dots Δ(ftsKLC) strains producing FtsKC from plasmid pFX150 (Materials and methods). The yellow zone indicates extend of the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3140498&req=5

pone-0022164-g003: Preferential interaction with the FtsK high activity region requires all domains of FtsK.Same legend as Figure 2. The grey curve corresponds to ftsKwt strains and is redrawn from figure 2. Recombination frequencies were measured at chosen loci in different ftsK mutant: Green dots: ftsKATP-; blue dots: Δ(ftsKγ); red dots Δ(ftsKLC) strains producing FtsKC from plasmid pFX150 (Materials and methods). The yellow zone indicates extend of the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).
Mentions: To investigate which features of FtsK are required for its preferential interaction with the FtsK high activity region, we first produced FtsKC detached from FtsKN from plasmid pFX150 in Δ(ftsKLC) strains (Materials and Methods). Production of FtsKC was induced using 0.03% arabinose, which yields a low but detectable level of protein [19]. As expected, this resulted in high recombination frequencies (red dots in Figure 3). Importantly, recombination frequencies were equivalent at all loci assayed (Figure 3). These results show that FtsKC can interact with the different chromosome regions at equivalent frequencies when unlinked from the division septum. It also follows that the XerCD recombinases have equal access to dif sites inserted into the different chromosome regions. We infer from these data that the restriction of FtsK activity to the FtsK high activity region depends on the tethering of FtsK to the division septum by FtsKN.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France.

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.

Methodology: 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.

Significance: 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.

Show MeSH
Related in: MedlinePlus