Nature of transforming deoxyribonucleic acid in calcium-treated Escherichia coli

Strike, Peter; Humphreys, G. O.; Roberts, Richard J.

doi:10.1128/jb.138.3.1033-1035.1979

Cited by 27 publications

(3 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…UV-damaged, chromosomally integrated plasmid DNA, on the other hand, survived equally on both recipients, indicating that it is not repaired. Strike et al (22) reported similar observations for the small, free plasmid NTP16, which they exposed to UV light and then assayed on CaCl2-treated suspensions of wild-type and a uvr mutant of Escherichia coli. Thus, the most plausible model for the transfer of integrated plasmids by genetic transformation is that the plasmid-flanking DNA regions invade the recipient chromosome at homologous sites as single strands, thus looping out the plasmid DNA as a single strand.…”

Section: Resultsmentioning

confidence: 70%

Mechanism of additive genetic transformation in Haemophilus influenzae

Stuy¹

1980

J Bacteriol

View full text Add to dashboard Cite

Transforming deoxyribonucleic acid (DNA) preparations from Haemophilus influenzae Rd strains carrying a chromosomally integrated, conjugative, antibiotic resistance transfer (R) plasmid were exposed to ultraviolet radiation and then assayed for antibiotic resistance transfer on sensitive wild-type Rd competent suspensions and on similar suspensions of a uvr-1 mutant unable to excise pyrimidine dimers. No host cell reactivation of resistance transfer (DNA repair) was observed. Parallel experiments with ethanol-precipitated, heated, free R plasmid DNA preparations gave much higher survival when assayed on the wildtype strain compared to the survival on the uvr-1 strain. These observations indicate that additive genetic transformation (in this case, the addition of the integrated R plasmid to the recipient genome) involves single-strand insertion. Additive genetic transformation describes the addition of long segments of donor DNA to the recipient cell genome through the process of DNA uptake by genetically competent cells. It was first reported for Haemophilus influenzae by Bendler (4), who studied the transfer of ampicillin resistance from some hospital isolates to strain Rd. He speculated that the donor strains could have possessed a chromosomally integrated plasmid. It was recently demonstrated

show abstract

Section: Resultsmentioning

confidence: 70%

Mechanism of additive genetic transformation in Haemophilus influenzae

Stuy¹

1980

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…We previously studied the repair of plasmid DNA in E. coli (9,13) by transforming UVdamaged DNA of the plasmid NTP16 into calcium-treated bacterial cells and showed that recA+-dependent repair contributes little to plasmid survival, whereas excision repair acts effectively on plasmid DNA. NTP16 is a nonconjugative plasmid (molecular weight, 5.6 x 106) which encodes resistance to ampicillin and kanamycin (5).…”

mentioning

confidence: 99%

“…The presence of such a function appears unlikely since (i) there was no increase in recombination frequency in an Hfr cross in which the recipient (either recA+ or recA-) carried resident pLV9 (data not shown); (ii) resident pLV9 did not enhance the survival of irradiated wild-type or recA mutant cells ( and AB1884(pLV9), O. Preparation of DNA, transformation of calcium-treated cells, and scoring of transformants were as described previously (5,9,13). In most cases, NTP16 survival was measured by scoring ampicillin transformants.…”

mentioning

confidence: 99%

Resident enhanced repair: novel repair process action on plasmid DNA transformed into Escherichia coli K-12

Strike¹,

Roberts²

1982

J Bacteriol

Self Cite

View full text Add to dashboard Cite

The survival of UV-irradiated DNA of plasmid NTP16 was monitored after its transformation into recipient cells containing an essentially homologous undamaged plasmid, pLV9. The presence of pLV9 resulted in a substantial increase in the fraction of damaged NTP16 molecules which survived in the recipicnt cells. This enhanced survival requires the host uvrA+ and uvrB+ gene products, but not the host recA+ gene product. The requirement for both homologous DNA and the uvrA+ and uvrB+ gene products suggests that a novel repair process may act on plasmid DNA. Possible mechanisms for this process are considered.The repair of DNA damaged by UV irradiation has been well studied in Escherichia coli and involves a complex series of pathways (1,4). Two main groups of repair pathways have been identified which operate in the dark: namely, the excision repair pathways which characteristically require the uvrA+, uvrB+, and uvrC+ gene products; and the postreplicational repair pathways which require the recA+ gene product. The sensitivities to UV irradiation displayed by mutant strains indicate that excision repair and post-replicational repair are of roughly equal importance for the survival of cells.We previously studied the repair of plasmid DNA in E. coli (9, 13) by transforming UVdamaged DNA of the plasmid NTP16 into calcium-treated bacterial cells and showed that recA+-dependent repair contributes little to plasmid survival, whereas excision repair acts effectively on plasmid DNA. NTP16 is a nonconjugative plasmid (molecular weight, 5.6 x 106) which encodes resistance to ampicillin and kanamycin (5).To find out whether recA+-dependent repair of NTP16 was limited by the absence of homologous DNA, we measured the survival of UVirradiated NTP16 in cells already containing the closely related plasmid pLV9. This latter plasmid was derived from NTP16 by hydroxylamine mutagenesis and is thought to carry a point mutation in the ampicillin resistance gene (G. 0. Humphreys, personal communication). Thus, the survival of NTP16 may be gauged by following the inheritance of ampicillin resistance.The resident pLV9 did increase the survival of the incoming NTP16 in wild-type cells and in recA and uvrC mutant cells (Fig. la, b, and c), but not in uvrA or uvrB mutant cells (Fig. lb and c). Additional experiments with pLV9-carrying derivatives of the recombinationor repair-defi-cient mutants revealed no other strains which failed to give enhanced survival of NTP16. In contrast, cells containing the plasmid pBR313, which is unrelated to NTP16, did not give enhanced survival (selecting in this instance for the stable acquisition of kanamycin resistance [Fig. la]).Increased survival has been observed in similar conditions with phage (prophage reactivation, multiplicity reactivation, and marker rescue) (2) and with transducing phage-plasmid hybrids (6). In each of these systems, the increase in survival appears to be because of recombination between the damaged molecule and its undamaged homolog. However, since the enhancement of NTP16 surviva...

show abstract

Repair of UV-Damaged DNA Transformed into E. coli

Strike

Roberts

1981

Chromosome Damage and Repair

View full text Add to dashboard Cite

Nature of transforming deoxyribonucleic acid in calcium-treated Escherichia coli

Cited by 27 publications

References 16 publications

Mechanism of additive genetic transformation in Haemophilus influenzae

Mechanism of additive genetic transformation in Haemophilus influenzae

Resident enhanced repair: novel repair process action on plasmid DNA transformed into Escherichia coli K-12

Repair of UV-Damaged DNA Transformed into E. coli

Contact Info

Product

Resources

About