Temperature Effects on the Rate of Ty Transposition

Paquin, Charlotte E.; Williamson, Valerie M.

doi:10.1126/science.226.4670.53

Cited by 148 publications

(91 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that annealing of primer to the mutant template is less efficient or the complex is slightly less stable. Perhaps priming is a temperature-limited step in Tyl transposition (16). A variety of models describing retroviral reverse transcription have been proposed and reviewed (2,5,(17)(18)(19).…”

Section: Discussionmentioning

confidence: 99%

The primer tRNA sequence is not inherited during Ty1 retrotransposition.

Lauermann

Boeke

1994

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

View full text Add to dashboard Cite

Yeast retrotransposon Tyl transposes through an RNA intermediate by a mechanism resembling retroviral replication. Long terminal repeat retroelements require primers for initiation of reverse transcription. The primer for minus-strand DNA synthesis is the 3' end of a cellular tRNA that base pairs to the complementary region of genomic RNA (the primer binding site). The genomic RNA of retroviruses and retrotransposons is shorter than its proviral DNA counterpart, lacking complete long terminal repeats. A variety of models have been proposed to describe how complete long terminal repeats are regenerated during reverse transcription. A common feature of these models is the requirement that the 3' portion of the primer tRNA be reverse-transcribed and then utilized in a strand-transfer reaction. We introduced a silent mutation into the Tyl primer binding site and followed its fate during a single cyde of reverse transcription to directly test this aspect of the reverse transcription model. We demonstrate that the tRNA sequence is not inherited by progeny Tyl elements during reverse transcription.Tyl, a long terminal repeat (LTR)-containing retrotransposon in the yeast Saccharomyces cerevisiae, transposes through an RNA intermediate (1). In this way, the Tyl life cycle resembles that of retroviruses. Like most DNA polymerases, Tyl-encoded reverse transcriptase (RT) is primerdependent. In LTR retroelements, the synthesis of minusstrand DNA is primed by an element-specific cellular tRNA (2). The Tyl primer is the initiator tRNAMet (3).The RNA genomes of LTR retroelements contain a region complementary to the 3' end of primer tRNA called the primer binding site (PBS), located just downstream of the 5' LTR (2). The precise position of priming by tRNA is very important because it determines the 3' DNA end of the new DNA copy (Fig. 1) (2, 5). Genomic RNAs of retroviruses and LTR retrotransposons are shorter than proviral DNA, having just small terminal repeats at each end (see Fig. 1 for LTR domain nomenclature). Full-length DNA products with complete LTRs are regenerated during reverse transcription, a conserved process in LTR retroelements (2).A variety of models describe how the ends of LTR retroelements are regenerated during DNA synthesis (6, 7). According to these models, the minus-strand strong-stop DNA, the first discrete intermediate in DNA synthesis, is completed when tRNA-primed synthesis reaches the 5' end of the template RNA. The RNA portion of the resulting RNA-DNA hybrid is digested by the RT-associated RNase H. Nascent minus-strand strong-stop DNA, consisting of R-U5 sequences attached to primer tRNA (Fig. 1), is transferred and annealed to the 3' end of the genomic RNA via its complementary small terminal repeat sequence and can then be extended to the 5' end of this template. Plus-strand DNA synthesis commences from an RNase H-resistant oligoribonucleotide region at the upstream boundary ofthe 3' LTR, in PPT1. RT then proceeds toward the tRNA molecule covalentlyjoined to the minus-strand DNA templa...

show abstract

Section: Discussionmentioning

confidence: 99%

The primer tRNA sequence is not inherited during Ty1 retrotransposition.

Lauermann

Boeke

1994

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

View full text Add to dashboard Cite

show abstract

“…Ura + transformants harboring pGTy1H3CLA were grown on SC + 2% glucose medium lacking uracil, and selected Ura + transformants were then grown in liquid SC + 2% glucose medium lacking uracil at 30°over-night. Aliquots of these cultures were diluted and spread onto solid SC medium lacking uracil + 2% galactose to induce Ty1 retrotransposition, and were then grown at 20°or 30°to vary the level of retrotransposition (Ty1 mobility is restricted at 30°) (Paquin and Williamson 1984;Lawler et al 2002). Single colonies obtained after induction were grown on YPD medium to allow for loss of pGTy1H3CLA and analyzed for Ty1 copy number by qPCR using a Roche LightCycler 480.…”

Section: Methodsmentioning

confidence: 99%

Extension of Saccharomyces paradoxus Chronological Lifespan by Retrotransposons in Certain Media Conditions Is Associated with Changes in Reactive Oxygen Species

VanHoute

Maxwell

2014

Genetics

View full text Add to dashboard Cite

Retrotransposons are mobile DNA elements present throughout eukaryotic genomes that can cause mutations and genome rearrangements when they replicate through reverse transcription. Increased expression and/or mobility of retrotransposons has been correlated with aging in yeast, Caenorhabditis elegans, Drosophila melanogaster, and mammals. The many copies of retrotransposons in humans and various model organisms complicate further pursuit of this relationship. The Saccharomyces cerevisiae Ty1 retrotransposon was introduced into a strain of S. paradoxus that completely lacks retrotransposons to compare chronological lifespans (CLSs) of yeast strains with zero, low, or high Ty1 copy number. Yeast chronological lifespan reflects the progressive loss of cell viability in a nondividing state. Chronological lifespans for the strains were not different in rich medium, but were extended in high Ty1 copy-number strains in synthetic medium and in rich medium containing a low dose of hydroxyurea (HU), an agent that depletes deoxynucleoside triphosphates. Lifespan extension was not strongly correlated with Ty1 mobility or mutation rates for a representative gene. Buffering deoxynucleoside triphosphate levels with threonine supplementation did not substantially affect this lifespan extension, and no substantial differences in cell cycle arrest in the nondividing cells were observed. Lifespan extension was correlated with reduced reactive oxygen species during early stationary phase in high Ty1 copy strains, and antioxidant treatment allowed the zero Ty1 copy strain to live as long as high Ty1 copy-number strains in rich medium with hydroxyurea. This exceptional yeast system has identified an unexpected longevity-promoting role for retrotransposons that may yield novel insights into mechanisms regulating lifespan.

show abstract

“…By increasing the potential genetic variability of a population, they may favour selection on quantitative traits (Mackay, 1985). Since environmental stress can increase transcription of some of them in yeast (Paquin and Williamson, 1984;Rolfe et al, 1986) and Drosophila (Strand and Macdonald, 1985), and may promote transposition in Drosophila (Junakovic et aL, 1986), these elements may play an important role in population adaptation.…”

Section: Introductionmentioning

confidence: 99%

Localisation polymorphism of mdg-1, copia, I and P mobile elements in genomes of Drosophila melanogaster, from data of inbred lines

Biémont

Gautier

1988

Heredity

View full text Add to dashboard Cite

Using data from in situ hybridisation of the giant chromosomes from salivary glands, mdg-1, I, copia, and P mobile element polymorphism was studied in 17 highly-inbred lines of Drosophila melanogaster and in the expected hybrids obtained from the theoretically-crossed inbred lines. The mean copy numbers of each element on the inbred lines were close and equal to 16-8 for mdg-1, 17•5 for I, 178 for copia and 186 for P (these values included the insertions in the centromeric regions). The P element differed from the other three for variance in copy number and distribution of the number of insertion site occurrences. A low frequency of X-linked copia element insertions (as compared with frequency of insertions in the other chromosomes) was reported, suggesting that natural selection acts against insertional deleterious mutations of this element. Such a low frequency of X-linked insertions was not observed for the other three elements. The mdg-1, I and copia element copy numbers were positively correlated, thus leading to lines with high or low copy number. No correlation was observed between the P element copy number and the numbers of mdg-1, I and copia elements. Moreover, a genomic control of copy number was detected for mdg-1, I and copia, but not for P. The number of labelling sites, the number of copies, the number of heterozygous insertion sites, and various indices of genetic variability were estimated from the expected hybrids obtained from the theoretically-crossed inbred lines; the calculated numbers of labelling sites for mdg-1 and I did not differ from those obtained directly from the initial wild-derived population (we had no estimate of the number of labelling sites available in this population for copia and P). An average proportion of heterozygous sites of 086, 092, 0•90 and 094, and an average number of copies of 33, 35, 38 and 37 were found in the theoretical hybrids for the mdg-1, I, copia and P elements, respectively.

show abstract

Temperature Effects on the Rate of Ty Transposition

Cited by 148 publications

References 9 publications

The primer tRNA sequence is not inherited during Ty1 retrotransposition.

The primer tRNA sequence is not inherited during Ty1 retrotransposition.

Extension of Saccharomyces paradoxus Chronological Lifespan by Retrotransposons in Certain Media Conditions Is Associated with Changes in Reactive Oxygen Species

Localisation polymorphism of mdg-1, copia, I and P mobile elements in genomes of Drosophila melanogaster, from data of inbred lines

Contact Info

Product

Resources

About