RecA protein of <i>Escherichia coli</i> and chromosome partitioning

Zyskind, Judith W.; Svitil, A L; Stine, W. Blaine; Biery, Matthew C.; Smith, Douglas W.

doi:10.1111/j.1365-2958.1992.tb01429.x

Cited by 48 publications

(12 citation statements)

References 69 publications

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“…Furthermore, when DNA degradation in recA derivatives was stimulated by UV, the number of anucleate cells was correspondingly increased. These findings support the conclusion that anucleate cells of recA strains result mainly from extensive DNA degradation (5,42), rather than being caused by uneven chromosome distribution during cell division, which was also proposed as a possibility (51). However, our results do not exclude certain involvement of RecA protein in the maintenance of chromosome structure, as well as in the regulation of chromosome positioning within a cell.…”

Section: Discussioncontrasting

confidence: 33%

“…The loss of DNA in such cells was attributed to DNA degradation initiated by the RecBCD (ExoV) nuclease at sites of unrepaired DNA breaks (5,42,48). As estimated by microscopic analysis of bacteria with DAPI-stained chromosomes, exponential cultures of recA mutants produce 5 to 13% anucleate cells (20,51) (Table 2). Such a frequency is enormously high, given the fact that anucleate cells represent less than 0.03% of the cell populations of wild-type strains (19).…”

Section: Resultsmentioning

confidence: 99%

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Roles of ExoI and SbcCD Nucleases in “Reckless” DNA Degradation inrecAMutants ofEscherichia coli

et al. 2009

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Exponentially growing recA mutant cells of Escherichia coli display pronounced DNA degradation that starts at the sites of DNA damage and depends on RecBCD nuclease (ExoV) activity. As a consequence of this "reckless" DNA degradation, populations of recA mutants contain a large proportion of anucleate cells. We have found that both DNA degradation and anucleate-cell production are efficiently suppressed by mutations in the xonA (sbcB) and sbcD genes. The suppressive effects of these mutations were observed in normally grown, as well as in UV-irradiated, recA cells. The products of the xonA and sbcD genes are known to code for the ExoI and SbcCD nucleases, respectively. Since both xonA and sbcD mutations are required for strong suppression of DNA degradation while individual mutations have only a weak suppressive effect, we infer that ExoI and SbcCD play partially redundant roles in regulating DNA degradation in recA cells. We suggest that their roles might be in processing (blunting) DNA ends, thereby producing suitable substrates for RecBCD binding.

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Section: Discussioncontrasting

confidence: 33%

Section: Resultsmentioning

confidence: 99%

Roles of ExoI and SbcCD Nucleases in “Reckless” DNA Degradation inrecAMutants ofEscherichia coli

et al. 2009

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“…One possible explanation is the formation of dimers independently of recA, for example, by a phage-encoded recombinase. Moreover, it is difficult to microscopically distinguish chromosome dimers and chromosome catenates, which are interlinked forms of two chromosomes that also prevent segregation and which were observed before in E. coli recA mutants (24,31). We obtained similar results with a different B. subtilis wild-type strain, YB886, which is cured of the SP␤ phage (see Table S1 and Fig S1A in the supplemental material).…”

Section: Resultssupporting

confidence: 71%

Two DNA Translocases Synergistically Affect Chromosome Dimer Resolution inBacillus subtilis

2011

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In Bacillus subtilis, chromosome dimers that block complete segregation of sister chromosomes arise in about 15% of exponentially growing cells. Two dedicated recombinases, RipX and CodV, catalyze the resolution of dimers by site-specific recombination at the dif site, which is located close to the terminus region on the chromosome. We show that the two DNA translocases in B. subtilis, SftA and SpoIIIE, synergistically affect dimer resolution, presumably by positioning the dif sites in close proximity, before or after completion of cell division, respectively. Furthermore, we observed that both recombinases, RipX and CodV, assemble on the chromosome at the dif site throughout the cell cycle. The preassembly of recombinases probably ensures that dimer resolution can occur rapidly within a short time window around cell division.During the course of the bacterial cell cycle, chromosomes need to be faithfully replicated and distributed to ensure that both daughter cells inherit a complete copy of the genetic information. However, the replication of circular chromosomes can lead to a covalently interlinked form of the chromosome (dimer), which results from an odd number of recombination events during replication and cannot be segregated. In Escherichia coli, dimers are resolved by an elaborate system of site-specific recombinases (XerD and XerC), (6) for recombination at the dif site, which is located near the terminus region of the chromosome (22). XerC and XerD are both members of the tyrosine recombinase family and catalyze the formation and resolution of a Holliday junction intermediate at dif, where each recombinase mediates a strand exchange reaction (7). The action of the XerCD recombinases is regulated and facilitated by the FtsK protein, which arranges the dif sites in close proximity and directly activates XerD. FtsK is recruited to the division septum as a component of the cell division machinery via its N-terminal domain, which anchors the protein in the membrane and is additionally essential for cell division (9, 30). The C-terminal domain is an ATP-dependent DNA translocase that moves DNA at very high rates (15,19) and in a spatially directed manner. Directionality of DNA translocation is predetermined by the orientation of short polar sequences on the chromosome (FtsK-orienting polar sequences [KOPS]), which are recognized by the FtsK␥ domain and permit the loading of FtsK onto the DNA in one specific orientation (14). KOPS are distributed over the chromosome and oriented toward the terminus of replication, where they are found at a high frequency (3). By KOPS-guided directed DNA translocation, FtsK arranges the duplicated dif sites in close proximity at the division septum and thereby facilitates dimer resolution (4). Additionally, FtsK directly activates the catalytic state of XerD and is therefore essential for effective chromosome dimer resolution (1, 28).The concept of site-specific recombination to resolve chromosome dimers is widely conserved among bacteria and archaea, and in most cases bacteri...

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“…The growth rates were determined by measuring the optical density of the cultures at 450 nm. The thr : : Tn10dnaC2 (Withers & Bernander, 1998), DdatA : : Kan (Kitagawa et al, 1998) and recA938 : : Cam (Zyskind et al, 1992) alleles were transferred by P1 transduction from MG1655dnaC2, RSD448 and ALS972, respectively, to the recipient strains listed in Table 1. W3110dnaC2 and MOR165 (W3110DdatAdnaC2) were transformed with MiniR1 or MiniR1-datA (Morigen et al, 2001) by electroporation.…”

Section: Methodsmentioning

confidence: 99%

The Escherichia coli datA site promotes proper regulation of cell division

Flåtten

Skarstad

2014

Microbiology

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In Escherichia coli inhibition of replication leads to a block of cell division. This checkpoint mechanism ensures that no cell divides without having two complete copies of the genome to pass on to the two daughter cells. The chromosomal datA site is a 1 kb region that contains binding sites for the DnaA replication initiator protein, and which contributes to the inactivation of DnaA. An excess of datA sites provided on plasmids has been found to lead to both a delay in initiation of replication and in cell division during exponential growth. Here we have investigated the effect of datA on the cell division block that occurs upon inhibition of replication initiation in a dnaC2 mutant. We found that this checkpoint mechanism was aided by the presence of datA. In cells where datA was deleted or an excess of DnaA was provided, cell division occurred in the absence of replication and anucleate cells were formed. This finding indicates that loss of datA and/or excess of DnaA protein promote cell division. This conclusion was supported by the finding that the lethality of the division-compromised mutants ftsZ84 and ftsI23 was suppressed by deletion of datA, at the lowest non-permissive temperature. We propose that the cell division block that occurs upon inhibition of DNA replication is, at least in part, due to a drop in the concentration of the ATP-DnaA protein. INTRODUCTIONIn Escherichia coli cell division involves the formation of a septum that separates the cell into two daughter cells. It is crucial that the two daughter nucleoids are segregated into each half of the cell, so that each daughter cell receives a copy of the genetic material and that none of the nucleoids are trapped in the septum. To ensure this, cell division and chromosome segregation are highly regulated processes involving a number of different proteins (see Egan & Vollmer, 2013;Harry et al., 2006;and Weiss, 2004, for reviews), the most studied being FtsZ. This protein polymerizes to form a ring-like structure at the site of division and serves as a scaffold for recruitment of other division proteins (Bi & Lutkenhaus, 1991). How the timing of the formation of the FtsZ ring is regulated is not clear.It is known that the chromosome replication cycle is independent of the cell division cycle, but that cell division is dependent on chromosome replication (Boye & Nordström, 2003; Nordström et al., 1991). That is, a blockage of chromosome replication stops cell division (Helmstetter & Pierucci, 1968;Walker & Pardee, 1968). Thus, a checkpoint mechanism must exist. The mechanism ensures that cell division does not occur in the absence of replication and thus prevents the formation of DNA-free (anucleate) daughter cells (Boye & Nordström, 2003; Nordström et al., 1991). Whether this mechanism is related to other regulatory circuits necessary for coupling the division cycle to cell physiology and to the growth rate of the cells, is not clear (see Haeusser & Levin, 2008, for a review).The DnaA protein is one of the main players in initiation of replica...

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RecA protein of Escherichia coli and chromosome partitioning

Cited by 48 publications

References 69 publications

Roles of ExoI and SbcCD Nucleases in “Reckless” DNA Degradation inrecAMutants ofEscherichia coli

Roles of ExoI and SbcCD Nucleases in “Reckless” DNA Degradation inrecAMutants ofEscherichia coli

Two DNA Translocases Synergistically Affect Chromosome Dimer Resolution inBacillus subtilis

The Escherichia coli datA site promotes proper regulation of cell division

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