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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

KOPS recognition is not required for preferential interaction of FtsK with the FtsK high activity region.Same legend as Figure 2 and 3. Grey curve: ftsKwt, redrawn from figure 2; red dots ftsKKOPSblind. The yellow zone indicates the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).
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pone-0022164-g004: KOPS recognition is not required for preferential interaction of FtsK with the FtsK high activity region.Same legend as Figure 2 and 3. Grey curve: ftsKwt, redrawn from figure 2; red dots ftsKKOPSblind. The yellow zone indicates the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).

Mentions: Although FtsK can recognise and translocate any DNA in vitro, it does so preferentially with KOPS motifs [23], [27], [30]. This prompted us to investigate how the KOPS recognition activity controls the interaction of FtsK with the chromosome. We used the ftsKKOPSblind allele of FtsK, which does not recognise the KOPS motif and so translocates DNA in a non-oriented manner [23], [31], [33]. Inactivating KOPS recognition lowered recombination at the natural dif position (red dots in Figure 4). This is consistent with a reduced capacity of the FtsKKOPSblind protein to reach the position where KOPS orientations converge compared to the wild type FtsK and with the accompanying partial defect in chromosome dimer resolution in ftsKKOPSblind strains [31]. In contrast, recombination frequencies appeared unchanged at loci located inside the FtsK high activity region or in its left transition zone (compare red to grey dots in Figure 4). This shows that KOPS recognition is not required for FtsK to translocate this region. Importantly, the FtsK high activity region did not expand in ftsKKOPSblind compared to wt strains, showing that the restriction of FtsK activity to this region is not due to KOPS-mediated orientation of FtsK translocation. Indeed, recombination frequencies at loci located outside the FtsK high activity region were undistinguishable from that of FtsK-independent recombination (Figure 4). Thus, the FtsKKOPSblind protein is unable to translocate DNA at loci located outside the FtsK high activity region whereas the wild type FtsK can do so, although at a low frequency.


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)

KOPS recognition is not required for preferential interaction of FtsK with the FtsK high activity region.Same legend as Figure 2 and 3. Grey curve: ftsKwt, redrawn from figure 2; red dots ftsKKOPSblind. The yellow zone indicates 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-g004: KOPS recognition is not required for preferential interaction of FtsK with the FtsK high activity region.Same legend as Figure 2 and 3. Grey curve: ftsKwt, redrawn from figure 2; red dots ftsKKOPSblind. The yellow zone indicates the FtsK high activity region and the grey zone the FtsK-independent recombination background (see Figure 2).
Mentions: Although FtsK can recognise and translocate any DNA in vitro, it does so preferentially with KOPS motifs [23], [27], [30]. This prompted us to investigate how the KOPS recognition activity controls the interaction of FtsK with the chromosome. We used the ftsKKOPSblind allele of FtsK, which does not recognise the KOPS motif and so translocates DNA in a non-oriented manner [23], [31], [33]. Inactivating KOPS recognition lowered recombination at the natural dif position (red dots in Figure 4). This is consistent with a reduced capacity of the FtsKKOPSblind protein to reach the position where KOPS orientations converge compared to the wild type FtsK and with the accompanying partial defect in chromosome dimer resolution in ftsKKOPSblind strains [31]. In contrast, recombination frequencies appeared unchanged at loci located inside the FtsK high activity region or in its left transition zone (compare red to grey dots in Figure 4). This shows that KOPS recognition is not required for FtsK to translocate this region. Importantly, the FtsK high activity region did not expand in ftsKKOPSblind compared to wt strains, showing that the restriction of FtsK activity to this region is not due to KOPS-mediated orientation of FtsK translocation. Indeed, recombination frequencies at loci located outside the FtsK high activity region were undistinguishable from that of FtsK-independent recombination (Figure 4). Thus, the FtsKKOPSblind protein is unable to translocate DNA at loci located outside the FtsK high activity region whereas the wild type FtsK can do so, although at a low frequency.

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