Independent Positioning and Action of Escherichia coli Replisomes in Live Cells

Reyes‐Lamothe, Rodrigo; Possoz, Christophe; Danilova, Olessia; Sherratt, David J.

doi:10.1016/j.cell.2008.01.044

Cited by 267 publications

(363 citation statements)

References 43 publications

(48 reference statements)

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“…1F). The separation of the ori-proximal loci at ϳ13 min after replication initiation is in agreement with previous estimates of cohesion in the ori region (47). Loci ϳ200 kb downstream of the ori-proximal loci (ori3 and ori4), which were replicated ϳ6 min after the ori-proximal loci based on the ϳ34-kb ⅐ min Ϫ1 replication rate in these cells, separated ϳ8 min later, indicating that these loci (ori1, -2, -3, and -4) have similar periods of cohesion.…”

Section: Resultssupporting

confidence: 91%

“…3E and G). These data confirm the independent action of replisomes on sister replichores (47) and show that loci on different replichores not only segregate independently but do so in such a way that each is not influenced by inhibition of the replication-segregation of the other replichore.…”

supporting

confidence: 77%

“…A body of experimental evidence has indicated that the chromosome loci segregate sequentially after replication, with a relatively short period of cohesion (36,43,47,57). These data, in part, provided support for an "extrusion-capture" model for chromosome segregation in which a DNA replication factory located at a fixed cellular position pulls in the DNA to replicate and then expels the newly replicated sisters outward (34).…”

mentioning

confidence: 90%

“…dnaC(Ts) mutant cells were grown exponentially at 30°C and then shifted to the nonpermissive temperature (37°C) at an A 600 of ϳ0.1 to block replication initiation but allow completion of ongoing rounds of DNA synthesis. After 2 h, the cells were shifted back to 30°C for 5 min to allow initiation of DNA synthesis (47). The culture was subsequently split in two with rifampin added to one of them.…”

Section: Vol 192 2010 E Coli Origin Segregation 6147mentioning

confidence: 99%

“…These data, in part, provided support for an "extrusion-capture" model for chromosome segregation in which a DNA replication factory located at a fixed cellular position pulls in the DNA to replicate and then expels the newly replicated sisters outward (34). However, the demonstration that sister replisomes track independently along the DNA in slow-growing E. coli argues against this model (47). Other observations have led to the suggestion that the organization and properties of the E. coli chromosome lead to "segmented" chromosome segregation in which extensive regions of the chromosome segregate together (2,15).…”

mentioning

confidence: 95%

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Independent Segregation of the Two Arms of theEscherichia coli oriRegion Requires neither RNA Synthesis nor MreB Dynamics

Wang

Sherratt

2010

J Bacteriol

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The mechanism of Escherichia coli chromosome segregation remains elusive. We present results on the simultaneous tracking of segregation of multiple loci in the ori region of the chromosome in cells growing under conditions in which a single round of replication is initiated and completed in the same generation. Loci segregated as expected for progressive replication-segregation from oriC, with markers placed symmetrically on either side of oriC segregating to opposite cell halves at the same time, showing that sister locus cohesion in the origin region is local rather than extensive. We were unable to observe any influence on segregation of the proposed centromeric site, migS, or indeed any other potential cis-acting element on either replication arm (replichore) in the AB1157 genetic background. Site-specific inhibition of replication close to oriC on one replichore did not prevent segregation of loci on the other replichore. Inhibition of RNA synthesis and inhibition of the dynamic polymerization of the actin homolog MreB did not affect ori and bulk chromosome segregation.The chromosome of the extensively studied bacterium Escherichia coli undergoes simultaneous replication and segregation and has no apparent mitotic apparatus for chromosome segregation, a situation very different from that of eukaryotes, where replication and segregation occur in temporally separate periods of the cell cycle. An unsolved mystery of the bacterial cell cycle is how chromosome segregation takes place. Several mechanisms have been proposed to drive the segregation of origin and bulk DNA after replication. In one model, cell elongation is proposed to be a crucial factor, in which the two newly replicated origins are attached to the inner membrane and separated by cell growth between them along the long axis of the cell (25). However, it is now clear that elongation occurs throughout the cell and the movement of the origins is much faster than the rate of cell elongation, indicating that cell elongation alone is not responsible for segregation (55,60).Active partitioning systems were first found in low-copynumber plasmids, where they are required for stable inheritance by distributing the daughter plasmids to both daughter cells (reviewed in reference 14). These systems fall into two families; one uses the ParM actin and its associated protein and binding sites to drive newly replicated sister plasmids apart during cycles of actin polymerization and depolymerization (4, 19). The second parABS family is less well understood mechanistically, although ATP hydrolysis-dependent cycles of ParA movement appear to play a key role in the segregation process (48).Later, it was found that many bacterial chromosomes also utilize parABS systems for their segregation, for example, Bacillus subtilis (23, 37), Caulobacter crescentus (41), and both chromosomes of Vibrio cholerae (22). The typical chromosomal par locus consists of two genes, parA and parB (soj and spo0J in B. subtilis), and a cis-acting parS DNA element. ParB is a DNA-binding prote...

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Section: Resultssupporting

confidence: 91%

supporting

confidence: 77%