Induction of yeast Ty element transcription by ultraviolet light

Rolfe, Mark W.; Spanos, Ad; Banks, Geoffrey R.

doi:10.1038/319339a0

Cited by 84 publications

(45 citation statements)

References 27 publications

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“…Ty1 elements are activated at a transcriptional level by DNA damaging agents (39)(40)(41). In contrast, we found that telomere erosion activates transposition at the level of cDNA synthesis, clearly differentiating the response to telomere erosion from the response to mutagens.…”

Section: Discussionmentioning

confidence: 47%

Activation of a LTR-retrotransposon by telomere erosion

Scholes

Kenny

Gamache

et al. 2003

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

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Retrotransposons can facilitate repair of broken chromosomes, and therefore an important question is whether the host can activate retrotransposons in response to chromosomal lesions. Here we show that Ty1 elements, which are LTR-retrotransposons in Saccharomyces cerevisiae, are mobilized when DNA lesions are created by the loss of telomere function. Inactivation of telomerase in yeast results in progressive shortening of telomeric DNA, eventually triggering a DNA-damage checkpoint that arrests cells in G 2͞M. A fraction of cells, termed survivors, recover from arrest by forming alternative telomere structures. When telomerase is inactivated, Ty1 retrotransposition increases substantially in parallel with telomere erosion and then partially declines when survivors emerge. Retrotransposition is stimulated at the level of Ty1 cDNA synthesis, causing cDNA levels to increase 20-fold or more before survivors form. This response is elicited through a signaling pathway that includes Rad24, Rad17, and Rad9, three components of the DNAdamage checkpoint. Our findings indicate that Ty1 retrotransposons are activated as part of the cellular response to telomere dysfunction.

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Section: Discussionmentioning

confidence: 47%

Activation of a LTR-retrotransposon by telomere erosion

Scholes

Kenny

Gamache

et al. 2003

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

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“…It is more likely that switching results from reversible, site-specific rearrangements or transposition of genomic DNA. There are many examples of switching in prokaryotes (Silverman & Simon, 1983;Borst & Greaves, 1987) and eukaryotes (Hicks et al, 1977;Borst & Greaves, 1987) in which such mechanisms have been elucidated, and transposition of Ty elements in Saccharomyces cerevisiae has been demonstrated to be stimulated through UV-induced increases in Ty transcript levels (Rolfe et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Bidirectional Stimulation of the White-Opaque Transition of Candida albicans by Ultraviolet Irradiation

Morrow

Anderson²,

Wilson³

et al. 1989

Microbiology

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1201Most strains of Candida albicans are capable of switching spontaneously and at high frequency between a number of phenotypes distinguishable by colony morphology. The switching frequency of Candida albicans strain WO-1 between two predominant phenotypes, 'white' and 'opaque', and a minor phenotype, 'fuzzy', increased dramatically with low doses of ultraviolet irradiation that killed less than 20% of the population. The ultraviolet irradiation effect continued to be expressed over many generations as evidenced by stimulated sectoring. Ultraviolet irradiation stimulated switching in both the white-to-opaque and opaque-to-white direction, suggesting that a common mechanism functions in both directions.

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“…Furthermore, much experimentation has shown that molecular hybrids between even rather closely related LTR retrotransposons are inactive for transposition. There is evidence that LTR retrotransposons in a variety of host organisms respond to global cellular regulatory pathways, including DNA damage pathways (Strand and McDonald 1985;Rolfe et al 1986;McEntee and Bradshaw 1988). Thus, the latter explanation seems more plausible.…”

Section: A Hybrid Dysgenesis-like Phenomenonmentioning

confidence: 99%

An env-like protein encoded by a Drosophila retroelement: evidence that gypsy is an infectious retrovirus.

Song¹,

Gerasimova²,

Kurkulos³

et al. 1994

Genes Dev.

250

185

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The gypsy element of Drosophila differs from most LTR retrotransposons in containing a third open reading frame that resembles retroviral env genes. The protein encoded by ORF3 is glycosylated and processed, like all retroviral envelope proteins. The protein is expressed at high levels in fly strains in which gypsy elements are active. In these strains the protein is found primarily in viral particles. When larvae of fly strains in which gypsy is normally inactive are exposed to sucrose gradient fractions containing these particles, a high level of gypsy insertion activity is observed in their progeny. Thus, gypsy has the expected properties of an insect retrovirus. [Key Words: Drosophila; mutagenesis; transposable element; insect retrovirus] Received May 6, 1994; revised version accepted July 11, 1994.The gypsy element of Drosophila melanogaster has been classified traditionally as a long terminal repeat (LTR) retrotransposon; however, it is one of a small group of LTR retrotransposons from insects that are unusual in that they contain three open reading frames (ORFs). In these retroelements, the first two ORFs correspond to retroviral gag and poi, whereas ORF3 is of unknown function but corresponds in size and genomic location to retroviral env (Fig. 1). All elements with three ORFs described so far are from insects, either Drosophila or the lepidopteran Trichoplusia ni. Recent results have shown that in two elements encoding an ORF3, gypsy and tom, a subgenomic mRNA similar in structure to retroviral env mRNAs can be found (P61isson et al. 1994;Tanda et al. 1994). In the case of gypsy, this transcript is observed only in certain strains in which gypsy transpositional activity is high (P41isson et al. 1994). The primary sequences of the encoded ORF3 proteins of these elements are quite variable and show no obvious similarity to retroviral Env proteins. However, retroviral Env proteins are themselves very variable in primary sequence. Like retroviral Env proteins, the proteins encoded by "retrotransposon" ORF3s contain a putative transmembrane domain near their carboxyl terminus, multiple putative N-glycosylation sites, and putative protease cleavage sites (resembling the cleavage sites in a variety of retroviral Env proteins) at conserved positions (Fig. 1 }. These features of gypsy and the other ORF3-containing insect retrotransposons have prompted the suggestion that these elements may represent endogenous insect retro- viruses (Boeke 1988;Boeke and Corces 1989;Coffin 1993).To address the question of whether gypsy represents a virus or a transposon more directly, we have turned to the use of Drosophila strains that show genetic instabilities associated with high-frequency insertion by gypsy elements. These strains are characterized by a large number of full-length gypsy elements in the euchromatin, appearance of gypsy insertion mutations at high frequency, and the presence of both large amounts of gypsy full-length RNA and spliced ORF3 mRNA (P61isson et al. 1994; N. Prud'homme, M. Gans, M. Masson, C. Ter...

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Induction of yeast Ty element transcription by ultraviolet light

Cited by 84 publications

References 27 publications

Activation of a LTR-retrotransposon by telomere erosion

Activation of a LTR-retrotransposon by telomere erosion

Bidirectional Stimulation of the White-Opaque Transition of Candida albicans by Ultraviolet Irradiation

An env-like protein encoded by a Drosophila retroelement: evidence that gypsy is an infectious retrovirus.

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