Repair of DNA double-strand breaks in Escherichia coli, which requires recA function and the presence of a duplicate genome

Krasin, Frank; Hutchinson, Franklin

doi:10.1016/0022-2836(77)90120-6

Cited by 233 publications

(104 citation statements)

References 31 publications

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“…It has been observed that the larger, more voluminous, bacilli such as Bacillus cereus and Bacillus megaterium contain two copies of the chromosome, whereas the spores of B. subtilis contain only one (26, 28), and furthermore, it has been found that these larger bacilli have increased resistance to ionizing radiation over the smaller bacilli (28). Similarly, cultures of E. coli grown on minimal media, with one to two chromosomes per cell, were found to be more sensitive to radiation than cultures grown in rich media, with two to eight chromosomes per cell (38), and Saccharomyces cerevisiae haploid strains are more radiation-sensitive than are diploid and tetraploid strains (39). Finally, the highly DNA damage-resistant Deinococcus radiodurans has been observed to exhibit recA-dependent interchromosomal recombination between the four copies of its genome as its second step for recovery after exposure to extreme doses of ionizing radiation (40,41).…”

Section: Discussionmentioning

confidence: 99%

DNA replication during sporulation in Myxococcus xanthus fruiting bodies

Tzeng

Singer

2005

Proc. Natl. Acad. Sci. U.S.A.

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During the developmental process of the Gram-negative soil bacterium Myxococcus xanthus, vegetatively growing rod cells differentiate to ultimately become metabolically quiescent and environmentally resistant myxospores encased within fruiting bodies. This program, initiated by nutrient deprivation, is propagated by both cell-autonomous and cell-nonautonomous signals. Our goal was to determine whether M. xanthus, like many other developmental systems, uses cell-cycle cues to regulate and control its developmental program. To address this question, the DNA replication cycle was used as a marker to monitor progression through the cell cycle in vegetative, stationary, and developing M. xanthus populations. Using flow cytometry, quantitative fluorescence microscopy, and FISH to establish the chromosome copy number of myxospores, it was determined that vegetatively growing cells contain one to two copies of the genome, but upon entry into stationary phase, the chromosome copy number drops to a single copy. Of particular interest, fruiting body-derived myxospores contain a specific two-chromosome DNA complement with both origin and terminus regions localized to the periphery of the myxospore. We speculate that this duplication of genetic information in the myxospore would help assure viability during germination by providing a second copy of each gene. The results of this study imply that not only is DNA replication tightly regulated during the developmental process of M. xanthus, but that there are also regulatory mechanisms to ensure that all myxospores acquire two copies of the chromosome.development ͉ chromosome copy number ͉ myxospore

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Section: Discussionmentioning

confidence: 99%

DNA replication during sporulation in Myxococcus xanthus fruiting bodies

Tzeng

Singer

2005

Proc. Natl. Acad. Sci. U.S.A.

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“…Various observations obtained with yeast strongly suggest that meiosis-specific DSBs occurring transiently at many locations in the genome initiate meiotic gene conversion and crossing over (Sun et al, 1989;Bishop et al, 1992;Wu and Lichten, 1994). DSB repair requires homologous recombination functions (Krasin and Hutchinson, 1977;Bishop et al, 1992;Shinohara et al, 1992). In fact, in the absence of the functions, a single DSB in the E. coli chromosome is lethal (Murialdo, 1988).…”

Section: Possible Roles Of Rdr In Dsb Repairmentioning

confidence: 99%

DNA replication triggered by double-stranded breaks in E. coli: Dependence on homologous recombination functions

Asai

Bates

Kogoma

1994

Cell

113

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SummaryHomologous recombination-dependent DNA replication (RDR) of a λ cos site-carrying plasmid is demonstrated in E. coli cells when the cells express λ terminase that introduces a double-stranded break into the cos site. RDR occurs in normal wild-type cells if the plasmid also contains the recombination hotspot χ. χ is dispensable when cells are induced for the SOS response or contain a recD mutation. recBC sbcA mutant cells are also capable of RDR induction. A recN mutation greatly reduces RDR in normal cells, but not in SOS-induced cells. RDR proceeds by the θ mode or rolling circle mode of DNA synthesis, yielding covalently closed circular plasmid monomers or linear plasmid multimers, respectively. Previously described inducible stable DNA replication is considered to be a special type of RDR that starts exclusively from specific sites (or/Ms) on the chromosome.

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“…Also remarkable is DEIRA's ability to grow at 60 Gy͞h without any discernable effect on its growth rate (7). Because most organisms, generally, can tolerate so few DSBs (8), radiationinduced DSBs and their repair have been difficult to study. In DEIRA, however, there are so many DSBs in fully viable irradiated cells after high-dose irradiation that the steps in DSB repair can be monitored directly in mass culture (5,(9)(10)(11).…”

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confidence: 99%

Transcriptome dynamics of Deinococcus radiodurans recovering from ionizing radiation

Liu

Zhou

Omelchenko

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

358

414

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Deinococcus radiodurans R1 (DEIRA) is a bacterium best known for its extreme resistance to the lethal effects of ionizing radiation, but the molecular mechanisms underlying this phenotype remain poorly understood. To define the repertoire of DEIRA genes responding to acute irradiation (15 kGy), transcriptome dynamics were examined in cells representing early, middle, and late phases of recovery by using DNA microarrays covering Ϸ94% of its predicted genes. At least at one time point during DEIRA recovery, 832 genes (28% of the genome) were induced and 451 genes (15%) were repressed 2-fold or more. The expression patterns of the majority of the induced genes resemble the previously characterized expression profile of recA after irradiation. DEIRA recA, which is central to genomic restoration after irradiation, is substantially up-regulated on DNA damage (early phase) and down-regulated before the onset of exponential growth (late phase). Many other genes were expressed later in recovery, displaying a growth-related pattern of induction. Genes induced in the early phase of recovery included those involved in DNA replication, repair, and recombination, cell wall metabolism, cellular transport, and many encoding uncharacterized proteins. Collectively, the microarray data suggest that DEIRA cells efficiently coordinate their recovery by a complex network, within which both DNA repair and metabolic functions play critical roles. Components of this network include a predicted distinct ATP-dependent DNA ligase and metabolic pathway switching that could prevent additional genomic damage elicited by metabolism-induced free radicals.T he Gram-positive aerobic bacterium Deinococcus radiodurans R1 (DEIRA) has an extraordinary resistance to ␥-radiation and a wide range of other DNA-damaging conditions, including desiccation and oxidizing agents (1, 2). Ionizing radiation induces DNA double-stranded breaks (DSBs) that are the most lethal form of DNA damage (3). After acute exposures to 10 kGy, early stationary phase (ESP) DEIRA can reassemble its 3.285-Mbp genome, which consists of four haploid genomic copies per cell (4), from hundreds of DNA DSB fragments without lethality or induced mutagenesis (5, 6). Also remarkable is DEIRA's ability to grow at 60 Gy͞h without any discernable effect on its growth rate (7). Because most organisms, generally, can tolerate so few DSBs (8), radiationinduced DSBs and their repair have been difficult to study. In DEIRA, however, there are so many DSBs in fully viable irradiated cells after high-dose irradiation that the steps in DSB repair can be monitored directly in mass culture (5, 9-11). This characteristic has been exploited and used to examine the timing of DNA recombination (5, 10, 12) after high-dose irradiation and has revealed the sequential action of RecA-independent and -dependent pathways during repair (11).Comparative genomic and experimental analyses support the view that DEIRA's extreme radiation resistance phenotype is complex, likely determined collectively by an assortment o...

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Repair of DNA double-strand breaks in Escherichia coli, which requires recA function and the presence of a duplicate genome

Cited by 233 publications

References 31 publications

DNA replication during sporulation in Myxococcus xanthus fruiting bodies

DNA replication during sporulation in Myxococcus xanthus fruiting bodies

DNA replication triggered by double-stranded breaks in E. coli: Dependence on homologous recombination functions

Transcriptome dynamics of Deinococcus radiodurans recovering from ionizing radiation

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