Organization of sister origins and replisomes during multifork DNA replication in Escherichia coli

Fossum, Solveig; Crooke, Elliott; Skarstad, Kirsten

doi:10.1038/sj.emboj.7601871

Cited by 106 publications

(112 citation statements)

References 41 publications

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“…6b). In our experiments, initiation of DNA replication in the mother cell before cytokinesis cannot be attributed to multifork replication [26][27][28] because we never observe a new round of DNA replication to initiate until the previous round has finished.…”

Section: Resultsmentioning

confidence: 88%

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

et al. 2013

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During the bacterial cell cycle, chromosome replication and cell division must be coordinated with overall cell growth in order to maintain the correct ploidy and cell size. The spatial and temporal coordination of these processes in mycobacteria is not understood. Here we use microfluidics and time-lapse fluorescence microscopy to measure the dynamics of cell growth, division and chromosome replication in single cells of Mycobacterium smegmatis. We find that single-cell growth is size-dependent (large cells grow faster than small cells), which implicates a size-control mechanism in cell-size homoeostasis. Asymmetric division of mother cells gives rise to unequally sized sibling cells that grow at different velocities but show no differential sensitivity to antibiotics. Individual cells are restricted to one round of chromosome replication per cell division cycle, although replication usually initiates in the mother cell before cytokinesis and terminates in the daughter cells after cytokinesis. These studies reveal important differences between cell cycle organization in mycobacteria compared with better-studied model organisms.

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Section: Resultsmentioning

confidence: 88%

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

et al. 2013

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“…Further co-localization of replication forks during segregation of multi-fork chromosomes In E. coli it has been found that the SeqA protein may be involved in the organization of new DNA at the replication forks (Fossum et al, 2007;Hiraga et al, 1998;Molina & Skarstad, 2004). The structures formed by SeqA are largely independent of the exact numbers of replication forks, and seem to be present in numbers roughly proportional to cell size Odsbu et al, 2009).…”

Section: Simultaneous Replication Of Two Copies Of Chriimentioning

confidence: 99%

“…Three and four oriII foci have been observed in another similar microscopy study of LB-grown cells (Saint-Dic et al, 2008), supporting our result. Also, in E. coli, both separate and co-localized origins have been observed in the same cell (giving the unexpected number of three foci), depending on the growth conditions (Adachi et al, 2008;Fossum et al, 2007;Nielsen et al, 2007).…”

Section: Simultaneous Replication Of Two Copies Of Chriimentioning

confidence: 99%

“…A reason for this apparent discrepancy could be that the numbers of origin foci were taken by the authors to be equivalent to numbers of origins. However, if V. cholerae origins stay co-localized for some time after initiation, as shown for origins in rapidly growing E. coli (Fossum et al, 2007), the number of origins will be underestimated by this approach. Three and four oriII foci have been observed in another similar microscopy study of LB-grown cells (Saint-Dic et al, 2008), supporting our result.…”

Section: Simultaneous Replication Of Two Copies Of Chriimentioning

confidence: 99%

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Replication patterns and organization of replication forks in Vibrio cholerae

2011

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We have investigated the replication patterns of the two chromosomes of the bacterium Vibrio cholerae grown in four different media. By combining flow cytometry and quantitative real-time PCR with computer simulations, we show that in rich media, V. cholerae cells grow with overlapping replication cycles of both the large chromosome (ChrI) and the small chromosome (ChrII). In Luria-Bertani (LB) medium, initiation occurs at four copies of the ChrI origin and two copies of the ChrII origin. Replication of ChrII was found to occur at the end of the ChrI replication period in all four growth conditions. Novel cell-sorting experiments with marker frequency analysis support these conclusions. Incubation with protein synthesis inhibitors indicated that the potential for initiation of replication of ChrII was present at the same time as that of ChrI, but was actively delayed until much of ChrI was replicated. Investigations of the localization of SeqA bound to new DNA at replication forks indicated that the forks were co-localized in pairs when cells grew without overlapping replication cycles and in higher-order structures during more rapid growth. The increased degree of fork organization during rapid growth may be a means by which correct segregation of daughter molecules is facilitated.

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“…or fluorescently tagged SeqA protein (Brendler et al, 2000;Fossum et al, 2007;Hiraga et al, 1998;Molina & Skarstad, 2004;Onogi et al, 1999;Yamazoe et al, 2005). Formation of such SeqA foci depends on ongoing replication (Hiraga et al, 2000).…”

Section: Localization Of Replication Forks Is Changed During Compactionmentioning

confidence: 99%

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Odsbu

Skarstad

2014

Microbiology

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The nucleoids of undamaged Escherichia coli cells have a characteristic shape and number, which is dependent on the growth medium. Upon induction of the SOS response by a low dose of UV irradiation an extensive reorganization of the nucleoids occurred. Two distinct phases were observed by fluorescence microscopy. First, the nucleoids were found to change shape and fuse into compact structures at midcell. The compaction of the nucleoids lasted for 10-20 min and was followed by a phase where the DNA was dispersed throughout the cells. This second phase lasted for~1 h. The compaction was found to be dependent on the recombination proteins RecA, RecO and RecR as well as the SOS-inducible, SMC (structural maintenance of chromosomes)-like protein RecN. RecN protein is produced in high amounts during the first part of the SOS response. It is possible that the RecN-mediated 'compact DNA' stage at the beginning of the SOS response serves to stabilize damaged DNA prior to recombination and repair.

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Organization of sister origins and replisomes during multifork DNA replication in Escherichia coli

Cited by 106 publications

References 41 publications

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

Replication patterns and organization of replication forks in Vibrio cholerae

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

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