The same configuration of Ty elements promotes different types and frequencies of rearrangements in different yeast strains

Picologlou, Susan; Dicig, Mary; Kovarik, Paula; Liebman, Susan W.

doi:10.1007/bf00330604

Cited by 13 publications

(3 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mutation rates were calculated by the method of the median (17) and by fluctuation tests (20). Twenty-four cultures inoculated with 100 to 160 cells were grown at 30°C for 22 to have been described previously (27). Plasmid pSH2 (37a), derived from a partial EcoRI digest of TLC-1 (5; kindly supplied by Jim Broach) which removed 2,um sequences, was used as a probe to hybridize to Southern blots when canrl mutants were scanned.…”

Section: Materlils and Methodsmentioning

confidence: 99%

Mutations in RAD6, a yeast gene encoding a ubiquitin-conjugating enzyme, stimulate retrotransposition.

1990

View full text Add to dashboard Cite

The Saccharomyces cerevisiae DNA repair gene RAD6 encodes a ubiquitin-conjugating enzyme which polyubiquitinates histones in vitro. Here we show that mutations in rad6 increase the frequency of transposition of the retrotransposon Ty into the CANI and URA3 loci. Using isogenic RAD6 and rad6 strains, we measured a more than 100-fold increase in the spontaneous rate of retrotransposition due to rad6, although there was no increase in the Ty message level. This is the first time that a mutation in a host gene has been shown to result in an increased rate of retrotransposition.Retrotransposons such as Ty are common in eucaryotes. While they are not infectious, they otherwise resemble retroviruses in their structural organization and replication in viruslike particles via an RNA intermediate (for a review, see reference 1). The finding that two-to fourfold increases in the transcription of Ty message caused disproportionately large increases in Ty transposition led to speculation that the cell may exert controls on transposition at a posttranscriptional level (7). Possibly the extra Ty mRNA leads to a complete saturation of this hypothetical posttranscriptional regulatory system. Other evidence that the rate of Ty transposition is not simply proportional to the Ty message level comes from the observation that growth at a low temperature (17 versus 30°C) causes a 50-to 100-fold increase in the rate of Ty transposition without changing the level of Ty mRNA (24,25). One explanation of this observation is that the reverse transcriptase activity is optimal at low temperatures (10).Mutations in the Saccharomyces cerevisiae RAD6 gene may result in several phenotypes, including extreme sensitivity to DNA-damaging agents, lack of induced mutagenesis, defective sporulation, increased mitotic recombination, and an increased rate of spontaneous mutation (for a review, see reference 13). RAD6 encodes an E22ok enzyme which polyubiquitinates histones H2A and H2B in vitro (16, 35) and which may influence chromatin structure (16,29,35). Here we show that among the spontaneous mutations stimulated by rad6 are mutations due to the transposition of Ty elements. Since the yeast RAD6 protein may be analogous to a mammalian 20-kilodalton E2 ubiquitin-conjugating enzyme (16,26), these studies may be relevant to studies of the cellular mechanisms used to control the movements of retrotransposons and retroviruses in other eucaryotes. LP2752-4B and LP2752-4Brad6A and plasmid pR67 were kindly provided by Louise Prakash. N-152, also from Louise Prakash, is a rad6-3 mutant (28) and was derived from B-635, a cycl-115 mutant derived from D311-3A (a Iys2 hisi trp2), both kindly provided by Fred Sherman.Mutant isolation. A large number of independent colonies from each strain were used to inoculate individual slants of complete medium, YPD (32), which were grown at 30°C. Cells suspended from these slants were plated either to synthetic complete medium lacking arginine and containing 60 ,ug of canavanine per ml (-Arg +Can) (32) or to medium containin...

show abstract

Section: Materlils and Methodsmentioning

confidence: 99%

Mutations in RAD6, a yeast gene encoding a ubiquitin-conjugating enzyme, stimulate retrotransposition.

1990

View full text Add to dashboard Cite

show abstract

“…Such deletions occur at a frequency of -1 x 10-5/element, and possibly even higher (cf. Picologlou et al, 1988;Rothstein, 1979). Nevertheless, the extreme bottlenecks in effective population number, created by clonal replacements (Koch, 1974), will maintain such deletions at low frequencies -on the order of 1 X 10 -5, unless they result in a selective advantage.…”

Section: Factors Determining Ty Copy Number In Populationsmentioning

confidence: 99%

The population biology and evolutionary significance of Ty elements in Saccharomyces cerevisiae

1992

View full text Add to dashboard Cite

The basic structure and properties of Ty elements are considered with special reference to their role as agents of evolutionary change. Ty elements may generate genetic variation for fitness by their action as mutagens, as well as by providing regions of portable homology for recombination. The mutational spectra generated by Ty1 transposition events may, due to their target specificity and gene regulatory capabilities, possess a higher frequency of adaptively favorable mutations than spectra resulting from other types of mutational processes. Laboratory strains contain between 25-35 elements, and in both these and industrial strains the insertions appear quite stable. In contrast, a wide variation in Ty number is seen in wild isolates, with a lower average number/genome. Factors which may determine Ty copy number in populations include transposition rates (dependent on Ty copy number and mating type), and stabilization of Ty elements in the genome as well as selection for and against Ty insertions in the genome. Although the average effect of Ty transpositions are deleterious, populations initiated with a single clone containing a single Ty element steadily accumulated Ty elements over 1,000 generations. Direct evidence that Ty transposition events can be selectively favored is provided by experiments in which populations containing large amounts of variability for Ty1 copy number were maintained for approximately 100 generations in a homogeneous environment. At their termination, the frequency of clones containing 0 Ty elements had decreased to approximately 0.0, and the populations had became dominated by a small number of clones containing > 0 Ty elements. No such reduction in variability was observed in populations maintained in a structured environment, though changes in Ty number were observed. The implications of genetic (mating type and ploidy) changes and environmental fluctuations for the long-term persistence of Ty elements within the S. cerevisiae species group are discussed.

show abstract

“…Such events may also be caused by the Mol Gen Genet (2000) 263: 722±732 duplication of genes in non-allelic positions (Mikus and Petes 1982;Jackson and Fink 1985). Ty transposable elements are highly repeated sequences and act as a major substrate for ectopic recombination leading to rearrangements such as deletion, insertion, inversion (Rothstein et al 1987;Picologlou et al 1988) and reciprocal translocation (Roeder and Fink 1980). Ty has been reported to function as a mobile element in CLP (Chale and Fink 1980), notably by generating hotspots for transposition (Warmington et al 1986;Wicksteed et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Homologous recombination and transposition generate chromosome I neopolymorphism during meiosis in Saccharomyces cerevisiae

Neuvéglise¹,

Solano-Serena²,

Brignon

et al. 2000

Mol Gen Genet

View full text Add to dashboard Cite

We have studied the meiotic segregation of a chromosome length polymorphism (CLP) in the yeast Saccharomyces cerevisiae. The neopolymorphism frequently observed within the smallest chromosomes (I, VI, III and IX) is not completely understood. We focused on the analysis of the structure of chromosome I in 88 segregants from a cross between YNN295 and FL100trp. Strain FL100trp is known to carry a reciprocal translocation between the left arm of chromosome III and the right arm of chromosome I. PCR and Southern hybridization analyses were performed and a method for the rapid detection of chromosome I rearrangements was developed. Seven chromosome I types were identified among the 88 segregants. We detected 22 recombination events between homologous chromosomes I and seven ectopic recombination events between FL100trp chromosome III and YNN295 chromosome I. These recombination events occurred in 20 of the 22 tetrads studied (91%). Nine tetrads (41%) showed two recombination events. This showed that homologous recombination involving polymorphic homologues or heterologous chromosomes is the main source of neopolymorphism. Only one of the seven chromosome I variants resulted from a transposition event rather than a recombination event. We demonstrated that a Tyl element had transposed within the translocated region of chromosome I, generating mutations in the 3' LTR, at the border between U5 and PBS.

show abstract

The same configuration of Ty elements promotes different types and frequencies of rearrangements in different yeast strains

Cited by 13 publications

References 27 publications

Mutations in RAD6, a yeast gene encoding a ubiquitin-conjugating enzyme, stimulate retrotransposition.

Mutations in RAD6, a yeast gene encoding a ubiquitin-conjugating enzyme, stimulate retrotransposition.

The population biology and evolutionary significance of Ty elements in Saccharomyces cerevisiae

Homologous recombination and transposition generate chromosome I neopolymorphism during meiosis in Saccharomyces cerevisiae

Contact Info

Product

Resources

About