Differential inhibition of the initiation of DNA replication in stringent and relaxed strains of<i>Escherichia coli</i>

Guzmán, Elena C.; Carrillo, Francisco Javier Garrido; Jiménez‐Sánchez, Alfonso

doi:10.1017/s0016672300024265

Cited by 19 publications

(10 citation statements)

References 13 publications

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“…Recently these results were confirmed by Guzman et al (1988) who found that deprivation of isoleucine in a Rel" strain gives rise to amplification of pBR322 with a better yield than that following treatment with chloramphenicol (Hecker et al, 1985). The results of this study give further evidence that E. coli relA strains are able to amplify ColElrelated plasmids.…”

Section: Introductionsupporting

confidence: 74%

RelAmutation and pBR322 plasmid amplification in amino acid-starved cells ofEscherichia coli

Hecker

1989

Genet. Res.

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Plasmid pBR322 is amplified following amino-acid limitation in Escherichia coli rel A hosts. In rel A* hosts there was no significant amplification or a much smaller one. Plasmid amplification is due to the relA mutation; when the relA + allele is transferred into the relA mutant CP79 this strain no longer amplifies plasmid DNA during amino acid starvation. It is concluded that ppGpp is a negative effector of plasmid replication. Amplification is temperature dependent, being maximal at 32 °C and negligible at 37 °C.

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Section: Introductionsupporting

confidence: 74%

RelAmutation and pBR322 plasmid amplification in amino acid-starved cells ofEscherichia coli

Hecker

1989

Genet. Res.

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“…This was expected, because we have previously shown that this promoter is stringently controlled and inhibited by ppGpp (45,46), and stringently controlled promoters are also growth rate regulated (13). In Bacillus subtilis, induction of the stringent response leads to an inhibition of chromosomal replication (51); indications are that this is also true for E. c oli (26,51), so a component of the initiation machinery appears to respond to changes in ppGpp concentrations in manner similar to that of rRNA operons.…”

Section: Discussionmentioning

confidence: 77%

Expression of Escherichia coli dnaA and mioC genes as a function of growth rate

Chiaramello

Zyskind

1989

J Bacteriol

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The synthesis of specific cellular components related to the initiation process of DNA replication was correlated with changes in growth rate. The concentrations of DnaA protein and mioC mRNA were determined for cells grown at six different growth rates; both increased relative to either total protein or total RNA, respectively, as the growth rate increased. Expression from the chromosomal mioC promoter, which contains a DnaA protein-binding site, was not repressed when the DnaA protein concentration was increased and was not derepressed in a dnaA46 mutant at 42°C. The mioC transcript had a characteristic mRNA-type half-life of 1.51 min.The bacterial cell regulates the rate of DNA synthesis by controlling the initiation frequency of chromosomal replication. Initiation is at a fixed site, oriC, located at 84 min on the Escherichia coli genetic map ( Fig. 1) An RNA polymerase synthetic event appears to be required for initiation to occur (Zyskind, in press), and the single transcription event that to date has been linked to initiation function originates from the mioC promoter. Many modifications of oriC minichromosomes that involve deletions, insertions, or single-base mutations in the mioC promoter region cause a decrease in copy number and increase in instability, properties that are the result of a decrease in initiation frequency (17,34,55). Transcripts that enter oriC in the counterclockwise direction (Fig. 1) originate mainly from this promoter, as demonstrated in this study and by others (25a). The 3' ends of mioC transcripts are located at and near the RNA-DNA transitions that most likely result from priming of the leading strand (31,45,46,48).The mioC promoter is stringently controlled (45, 46). Most stringently controlled promoters are also under growth rate control, and the same nucleotide sequence in rRNA operon promoters appears to be responsible for both stringent * Corresponding author.control and growth-rate-dependent regulation (13). We have examined here whether the mioC promoter is growth rate regulated and whether transcripts originating only from the mioC promoter enter the origin or whether transcripts from the asnC promoter also reach oriC. Our approach was to use S1 nuclease protection by in vivo-generated transcripts of a probe that contained the 5' ends of both transcripts so that the intracellular concentration of each transcript in cells grown at different growth rates as well as relative to each other could be measured by densitometric analysis. Using total RNA isolated from E. coli cells grown at six different growth rates, we determined that most transcription reaching oriC originates from the mioC promoter and that the mioC transcript is growth rate regulated. The stability of the mioC transcript was examined and found to have a half-life of 1.51 min. MATERIALS AND METHODSBacterial strains and plasmids. The E. coli K-12 strain used for the growth rate regulation studies, EMG2 F+ XA, was provided by B. Bachmann. Strains EC559 F-argE3 his4 leu-6 proA2 thr-1 ara-14 galK2 lac YI thi-J...

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“…Replication of E. coli chromosome as well as oriC plasmids is inhibited during stringent response whereas in retA mutants, the replication proceeded when bacteria were starved for isoleucine but not for other amino acids (GUZMAN et al 1988, LEVINE ef al. 1991.…”

Section: Oricmentioning

confidence: 99%

“…Changes in transcription efficiency from many promoters are primary effects of ppGpp action. Although differences between DNA replication in amino acid-starved relA+ and relA-strains were demonstrated, these results were often controversial; in some cases starvation for a particular amino acid gave different results than for another one (GUZMAN et al 1988, HECKER et al 1983, 1985, HERMAN et al 1994a, b, LIN-CHAO and BREMER 1986, RIETHDORF et al 1989, W~GRZYN et al 1991a). Since ppGpp is the main effector of the stringent response (CASHEL and RUDD 1987) only investigation of the process in unstarved cells containing increased levels of ppGpp could eliminate the secondary effects of amino acid deprivation and allow to answer the following question: is DNA replication under stringent control?…”

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confidence: 99%

Effect of increased ppGpp concentration on DNA replication of different replicons in Escherichia coli

Herman¹,

Wèrzyn²

1995

J. Basic Microbiol.

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The plasmids harbouring the relA gene under an inducible promoter allowed us to increase the guanosine 5'-diphosphate-3'-diphosphate (ppGpp) concentration in Escherichia coli cells without any starvation and thus, to directly investigate the effect of ppGpp on DNA replication. We studied all types of replicons which were investigated previously in amino acid-starved bacteria and found that ColE1, oriC, lambda plasmid and pSC101 but not RK2 replicons are sensitive to high ppGpp level. To our knowledge, this paper presents the first direct evidence that replication of most, but not all, replicons is dependent on ppGpp concentration and thus, is under stringent control.

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Differential inhibition of the initiation of DNA replication in stringent and relaxed strains ofEscherichia coli

Cited by 19 publications

References 13 publications

RelAmutation and pBR322 plasmid amplification in amino acid-starved cells ofEscherichia coli

RelAmutation and pBR322 plasmid amplification in amino acid-starved cells ofEscherichia coli

Expression of Escherichia coli dnaA and mioC genes as a function of growth rate

Effect of increased ppGpp concentration on DNA replication of different replicons in Escherichia coli

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