RecA, Tus protein and constitutive stable DNA replication inEscherichia coli rnhA mutants

Kogoma, Tokio; Barnard, K G; Hong, Xiankang

doi:10.1007/bf00583907

Cited by 8 publications

(9 citation statements)

References 49 publications

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“…A combination of recG and rnhA mutations is lethal In the course of our previous studies on possible roles of homologous recombination on cSDR Kogoma et al, 1994), we had attempted and failed to introduce, by P1 phage-mediated transduction, the recG285::kan mutation into rnhA224 mutants although we had been able to combine any other rec mutations with the rnhA224 mutation. This suggested that simultaneous loss of RecG and RNase HI activities is lethal to the cell.…”

Section: Resultsmentioning

confidence: 99%

“…Previously we presented a model (Cao and Kogoma, 1993;Kogoma et al, 1994) which is radically different from the de novo formation model above. It is hypothesized that a persistent R-loop is formed by invasion of the duplex by a transcript that has just been synthesized and displaced from the template ( Figure 6B).…”

Section: Discussionmentioning

confidence: 95%

“…The dispensability of these rec gene products suggests that RecA is uniquely involved in the process of cSDR initiation. It has been proposed that RecA catalyzes annealing between a transcript and the template DNA strand, leading to an R-loop (Cao and Kogoma, 1993;Kogoma et al, 1994). These R-loops become origins (oriKs) of chromosome replication, at which DNA synthesis is primed by a X 174type of primosome (Masai et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Escherichia coli RecG and RecA proteins in R-loop formation.

1995

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Escherichia coli rnhA mutants devoid of RNase HI exhibit constitutive stable DNA replication, cSDR, which is thought to be initiated from R-loops stabilized in the absence of RNase HI. We found that a combination of an rnhA and a recG mutation is lethal to the cell. recG mutations that inactivate the helicase activity of RecG protein and inhibit reverse branch migration of Holliday junctions impart phenotypes resembling those of rnhA mutants. Thus, recG mutants display cSDR activity, and recG polA double mutants are inviable as are rnhA poUl double mutants. These results suggest that the RecG helicase has a role in preventing R-loop formation. A model that R-loops are formed by assimilation of RNA transcripts into the duplex DNA is discussed. The model further postulates that RecA protein catalyzes this assimilation reaction and that RecG protein counteracts RecA in this reaction, resolves R-loops by its helicase activity, or does both.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Escherichia coli RecG and RecA proteins in R-loop formation.

1995

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“…These results suggested that RecG, like RNase HI, plays an important role in the removal of R‐loops. R‐loops are thought to be required for the initiation of cSDR (Kogoma et al ., 1994; Hong et al ., 1995).…”

Section: Introductionmentioning

confidence: 99%

ATP-dependent resolution of R-loops at the ColE1 replication origin by Escherichia coli RecG protein, a Holliday junction-specific helicase

et al. 1997

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single strand DNA while RecG shows a 3Ј to 5Ј DNA Department of Molecular Microbiology, Research Institute for helicase activity (Tsaneva et al., 1993; Whitby et al., Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, 1994). Osaka 565, Japan In the RuvABC pathway, RuvC is a specific endonucle-1 Corresponding author ase that resolves Holliday junctions (Dunderdale et al., 1991;Iwasaki et al., 1991). RecG, which functions in The RecG protein of Escherichia coli is a DNA helicase the alternative pathway, has been suggested to promote that promotes branch migration of the Holliday juncjunction resolution by driving branch migration in the tions. We found that overproduction of RecG protein opposite direction from that promoted by RecA protein drastically decreased copy numbers of ColE1-type (Whitby et al., 1993;Whitby and Lloyd, 1995). These plasmids, which require R-loop formation between the authors proposed that RecG plays a role in preventing template DNA and a primer RNA transcript (RNA unproductive recombination by reversing the invasion of II) for the initiation of replication. RecG efficiently a 5Ј single-stranded DNA end into the homologous duplex inhibited in vitro ColE1 DNA synthesis in a reconstitu- . ted system containing RNA polymerase, RNase HI andThe recG and ruv genes play different roles in alternative DNA polymerase I. RecG promoted dissociation of mechanisms of stable DNA replication (SDR), which do RNA II from the R-loop in a manner that required not require the chromosomal replication origin (oriC), ATP hydrolysis. These results suggest that overDnaA initiator protein or concomitant protein synthesis produced RecG inhibits the initiation of replication (Asai and Kogoma, 1994a). Mutations in the ruv or recG by prematurely resolving the R-loops formed at the gene stimulate inducible SDR (iSDR), which is a part of replication origin region of these plasmids with its SOS responses, suggesting that this mode of SDR involves unique helicase activity. The possibility that RecG D-loops or Holliday junctions made by RecA (Asai and regulates the initiation of a unique mode of DNA Kogoma, 1994b). recG mutants, but not ruv mutants, replication, oriC-independent constitutive stable DNA stimulate constitutive SDR (cSDR), which was found replication, by its activity in resolving R-loops is disoriginally in RNase HI-defective (rnhA) mutants, and recG cussed.rnhA double mutants are inviable. These results suggested

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“…Bacteriophage T4 has been shown, both in vivo (42) (21). Thus, it is extremely unlikely that cSDR involves homologous recombination.…”

mentioning

confidence: 99%

D-loops and R-loops: alternative mechanisms for the initiation of chromosome replication in Escherichia coli

1994

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RecA, Tus protein and constitutive stable DNA replication inEscherichia coli rnhA mutants

Cited by 8 publications

References 49 publications

Escherichia coli RecG and RecA proteins in R-loop formation.

Escherichia coli RecG and RecA proteins in R-loop formation.

ATP-dependent resolution of R-loops at the ColE1 replication origin by Escherichia coli RecG protein, a Holliday junction-specific helicase

D-loops and R-loops: alternative mechanisms for the initiation of chromosome replication in Escherichia coli

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