Renaturation and DNA looping promoted by the SV40 large tumour antigen.

Schiedner, Gudrun; Wessel, Rainer; Scheffner, Martin; Stahl, Hans

doi:10.1002/j.1460-2075.1990.tb07485.x

Cited by 20 publications

(14 citation statements)

References 78 publications

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“…The Rep protein in E. coli might be involved in both repair and replication; UvrD helicase plays functions in both the excision step of the nucleotide excision repair catalyzed by the UvrABC complex and in mutagenesis; SV40 T antigen unwinds DNA at the replication origin in the initiation of viral DNA replication, is used as a DNA helicase in the elongation process. Moreover, T antigen seems also to be involved in DNA recombination and possesses an RNA helicase activity (Schiedner et al, 1990;Scheffner et al, 1989). In contrast, helicases might also have a unique specific role like DNA helicases associated with the primosome.…”

Section: Pif1 Is a Dna Helicasementioning

confidence: 99%

PIF1: a DNA helicase in yeast mitochondria.

et al. 1991

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The PIF1 gene is involved in repair and recombination of mitochondrial DNA (mtDNA). In this study, the PIF1 gene product, which cannot be identified in normal yeast cells, has been overproduced from the GALI promoter to detectable protein levels. Location of PIF1 in mitochondria has been shown by immunoelectron microscopy and in vivo import experiments using ts mas1 mutants deficient in the mitochondrial matrix‐localized processing protease. Overproduction of PIF1 protein in pif1 mutants restores mtDNA recombination proficiency but is toxic to yeast cells as observed by slower growth. The overproduced PIF1 protein, which is firmly associated with insoluble mitochondrial structures, has been partially purified in a mitochondrial nuclease deficient nuc1 strain by a procedure including solubilization by urea and renaturation by dialysis at alkaline pH. PIF1 is a single‐stranded (ss) DNA‐dependent ATPase and a DNA helicase which unwinds partially DNA duplexes in a 5′ to 3′ direction with respect to the ss DNA on which it binds first.

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Section: Pif1 Is a Dna Helicasementioning

confidence: 99%

PIF1: a DNA helicase in yeast mitochondria.

et al. 1991

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“…For binding of p53 to partially ds DNA (Figure 3), linear pUC8 DNA was incubated with I-exonuclease, to obtain 3' ss ends with a minimal length of 500 nt (for experimental details, see Schiedner et al, 1990).…”

Section: Methodsmentioning

confidence: 99%

“…Electron microscopy was carried out as described previously (Schiedner et al, 1990;Wessel et al, 1992). Micrographs were taken in a Zeiss EM 900 electron microscope.…”

Section: Assaysmentioning

confidence: 99%

p53-catalyzed annealing of complementary single-stranded nucleic acids.

et al. 1993

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'Corresponding author Communicated by R.Knippers p53 has been reported to inhibit the DNA helicase intrinsic to simian virus 40 large tumor antigen (T antigen). We found that inhibition is not restricted to T antigen, but also affects several other DNA and RNA helicases. Complexing of the helicases by the p53 protein as a possible inactivation mechanism could be excluded. Instead, the anti-helicase activity can be explained by our finding that p53 binds with high affinity to singlestranded nucleic acids and has a strong DNA-DNA and RNA-RNA annealing activity. We could also show that p53 is able to alter the secondary structure of RNA and/or to influence dynamic RNA-RNA interactions. These results, and the fact that the affinity of p53 to RNA is about one order of magnitude higher than to singlestranded DNA, imply an RNA-specific function of p53 in vivo.

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“…Protein interactions alone, as described above, cannot account for the increase we observed in RAD51 transcript levels within immortal cell lines, and in diploid fibroblasts upon T antigen introduction (Xia et aL 1997). Because T antigen bound to distal regions of DNA can oligomerize in the presence of magnesium ions, to effect DNA looping (Schiedner et aL 1990), the ability to physically associate distant regions of DNA may also contribute to its induction of recombination. Functional association between replication and recombination has also been observed for bacterial genomic DNA.…”

Section: Telomeric Recombination --Another Means To Justify An Endmentioning

confidence: 56%

Recombination and its roles in DNA repair, cellular immortalization and cancer

Shammas

Reis

1999

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Genetic recombination is the creation of new gene combinations in a cell or gamete, which differ from those of progenitor cells or parental gametes. In eukaryotes, recombination may occur at mitosis or meiosis. Mitotic recombination plays an indispensable role in DNA repair, which presumably directed its early evolution; the multiplicity of recombination genes and pathways may be best understood in this context, although they have acquired important additional functions in generating diversity, both somatically (increasing the immune repertoire) and in germ line (facilitating evolution). Chromosomal homologous recombination and HsRad51 recombinase expression are increased in both immortal and preimmortal transformed cells, and may favor the occurrence of multiple oncogenic mutations. Tumorigenesis in vivo is frequently associated with karyotypic instability, locus-specific gene rearrangements, and loss of heterozygosity at tumor suppressor loci - all of which can be recombinationally mediated. Genetic defects which increase the rate of somatic mutation (several of which feature elevated recombination) are associated with early incidence and high risk for a variety of cancers. Moreover, carcinogenic agents appear to quite consistently stimulate homologous recombination. If cells with high recombination arise, either spontaneously or in response to "recombinogens," and predispose to the development of cancer, what selective advantage could favor these cells prior to the occurrence of growth-promoting mutations? We propose that the augmentation of telomere-telomere recombination may provide just such an advantage, to hyper-recombinant cells within a population of telomerase-negative cells nearing their replicative (Hayflick) limit, by extending telomeres in some progeny cells and thus allowing their continued proliferation.

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Renaturation and DNA looping promoted by the SV40 large tumour antigen.

Cited by 20 publications

References 78 publications

PIF1: a DNA helicase in yeast mitochondria.

PIF1: a DNA helicase in yeast mitochondria.

p53-catalyzed annealing of complementary single-stranded nucleic acids.

Recombination and its roles in DNA repair, cellular immortalization and cancer

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