The Tn3 beta-lactamase gene acts as a hotspot for meiotic recombination in yeast.

Abstract Although genetic distances are often assumed to be proportional to physical distances, chromosomal regions with unusually high (hotspots) or low (coldspots) levels of meiotic recombination have been described in a number of genetic systems. In general, the DNA sequences responsible for these effects have not been determined. We report that the 5' region of the beta-lactamase (ampR) gene of the bacterial transposon Tn3 is a hotspot for meiotic recombination when inserted into the chromosomes of the yeast Saccharomyces cerevisiae. When these sequences are homozygous, both crossing over and gene conversion are locally stimulated. The 5' end of the beta-lactamase gene is about 100-fold "hotter" for crossovers than an average yeast DNA sequence.

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Effects of Homology, Size and Exchange on the Meiotic Segregation of Model Chromosomes in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/142.1.79 ◽

1996 ◽

Vol 142 (1) ◽

pp. 79-89 ◽

Cited By ~ 2

Author(s):

Lyle O Ross ◽

Susannah Rankin ◽

Michèle F Shuster ◽

Dean S Dawson

Keyword(s):

Saccharomyces Cerevisiae ◽

Dna Sequences ◽

Crossing Over ◽

Chromosome Size ◽

Meiotic Segregation ◽

Yeast Saccharomyces Cerevisiae ◽

Homologous Chromosomes ◽

Reciprocal Recombination ◽

Eukaryotic Organisms ◽

Meiosis I

In most eukaryotic organisms, chiasmata, the connections formed between homologous chromosomes as a consequence of crossing over, are important for ensuring that the homologues move away from each other at meiosis I. Some organisms have the capacity to partition the rare homologues that have failed to experience reciprocal recombination. The yeast Saccharomyces cerevisiae is able to correctly partition achiasmate homologues with low fidelity by a mechanism that is largely unknown. It is possible to test which parameters affect the ability of achiasmate chromosomes to segregate by constructing strains that will have three achiasmate chromosomes at the time of meiosis. The meiotic partitioning of these chromosomes can be monitored to determine which ones segregate away from each other at meiosis I. This approach was used to test the influence of homologous yeast DNA sequences, recombination intiation sites, chromosome size and crossing over on the meiotic segregation of the model chromosomes. Chrome some size had no effect on achiasmate segregation. The influence of homologous yeast sequences on the segregation of noncrossover model chromosomes was negligible. In meioses in which two of the three model chromosomes experienced a crossover, they nearly always disjoined at meiosis I.

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Meiotic Crossing Over Between Nonhomologous Chromosomes Affects Chromosome Segregation in Yeast

Genetics ◽

10.1093/genetics/146.1.69 ◽

1997 ◽

Vol 146 (1) ◽

pp. 69-78

Author(s):

Sue Jinks-Robertson ◽

Shariq Sayeed ◽

Tamara Murphy

Keyword(s):

Saccharomyces Cerevisiae ◽

Gene Conversion ◽

Chromosome Segregation ◽

Meiotic Recombination ◽

Southern Blot Analysis ◽

Meiotic Chromosome ◽

Crossing Over ◽

Yeast Saccharomyces Cerevisiae ◽

Reciprocal Translocations ◽

Ectopic Recombination

Meiotic recombination between artificial repeats positioned on nonhomologous chromosomes occurs efficiently in the yeast Saccharomyces cerevisiae. Both gene conversion and crossover eventS have been observed, with crossovers yielding reciprocal translocations. In the current study, 5.5-kb ura3 repeats positioned on chromosomes V and XV were used to examine the effect of ectopic recombination on meiotic chromosome segregation. Ura+ random spores were selected and gene conversion vs. crossover events were distinguished by Southern blot analysis. Approximately 15% of the crossover events between chromosomes V and XV were associated with missegregation of one of these chromosomes. The missegregation was manifest as hyperploid spores containing either both translocations plus a normal chromosome, or both normal chromosomes plus one of the translocations. In those cases where it could be analyzed, missegregation occurred at the first meiotic division. These data are discussed in terms of a model in which ectopic crossovers compete efficiently with normal allelic crossovers in directing meiotic chromosome segregation.

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INDUCTION OF INTRACHROMOSOMAL RECOMBINATION IN YEAST BY INHIBITION OF THYMIDYLATE BIOSYNTHESIS

Genetics ◽

10.1093/genetics/114.2.375 ◽

1986 ◽

Vol 114 (2) ◽

pp. 375-392

Author(s):

B A Kunz ◽

G R Taylor ◽

R H Haynes

Keyword(s):

Gene Conversion ◽

Dna Sequences ◽

Dna Hybridization ◽

Crossing Over ◽

Repeated Dna ◽

Yeast Saccharomyces Cerevisiae ◽

Haploid Strain ◽

Reciprocal Exchange ◽

Coli Plasmid ◽

Antifolate Drugs

ABSTRACT The biosynthesis of thymidylate in the yeast Saccharomyces cerevisiae can be inhibited by antifolate drugs. We have found that antifolate treatment enhances the formation of leucine prototrophs in a haploid strain of yeast carrying, on the same chromosome, two different mutant leu2 alleles separated by Escherichia coli plasmid sequences. That this effect is a consequence of thymine nucleotide depletion was verified by the finding that provision of exogenous thymidylate eliminates the increased production of Leu+ colonies. DNA hybridization analysis revealed that recombination, including reciprocal exchange, gene conversion and unequal sister-chromatid crossing over, between the duplicated genes gave rise to the induced Leu+ segregants. Although gene conversion unaccompanied by crossing over was responsible for the major fraction of leucine prototrophs, events involving reciprocal exchange exhibited the largest increase in frequency. These data show that recombination is induced between directly repeated DNA sequences under conditions of thymine nucleotide depletion. In addition, the results of this and previous studies are consistent with the possibility that inhibition of thymidylate biosynthesis in yeast may create a metabolic condition that provokes all forms of mitotic recombination.

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Crossover Interference in Saccharomyces cerevisiae Requires a TID1/RDH54- and DMC1-Dependent Pathway

Genetics ◽

10.1093/genetics/163.4.1273 ◽

2003 ◽

Vol 163 (4) ◽

pp. 1273-1286 ◽

Cited By ~ 3

Author(s):

Miki Shinohara ◽

Kazuko Sakai ◽

Akira Shinohara ◽

Douglas K Bishop

Keyword(s):

Saccharomyces Cerevisiae ◽

Meiotic Recombination ◽

Strand Break ◽

Tetrad Analysis ◽

Yeast Saccharomyces Cerevisiae ◽

Crossover Interference ◽

Meiotic Progression ◽

Invasion Stage ◽

Strand Invasion ◽

Dependent Pathway

Abstract Two RecA-like recombinases, Rad51 and Dmc1, function together during double-strand break (DSB)-mediated meiotic recombination to promote homologous strand invasion in the budding yeast Saccharomyces cerevisiae. Two partially redundant proteins, Rad54 and Tid1/Rdh54, act as recombinase accessory factors. Here, tetrad analysis shows that mutants lacking Tid1 form four-viable-spore tetrads with levels of interhomolog crossover (CO) and noncrossover recombination similar to, or slightly greater than, those in wild type. Importantly, tid1 mutants show a marked defect in crossover interference, a mechanism that distributes crossover events nonrandomly along chromosomes during meiosis. Previous work showed that dmc1Δ mutants are strongly defective in strand invasion and meiotic progression and that these defects can be partially suppressed by increasing the copy number of RAD54. Tetrad analysis is used to show that meiotic recombination in RAD54-suppressed dmc1Δ cells is similar to that in tid1; the frequency of COs and gene conversions is near normal, but crossover interference is defective. These results support the proposal that crossover interference acts at the strand invasion stage of recombination.

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Competition Between Adjacent Meiotic Recombination Hotspots in the Yeast Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/145.3.661 ◽

1997 ◽

Vol 145 (3) ◽

pp. 661-670 ◽

Cited By ~ 1

Author(s):

Qing-Qing Fan ◽

Fei Xu ◽

Michael A White ◽

Thomas D Petes

Keyword(s):

Saccharomyces Cerevisiae ◽

Meiotic Recombination ◽

Telomeric Sequence ◽

Coding Region ◽

Dna Breaks ◽

Local Formation ◽

Yeast Saccharomyces Cerevisiae ◽

Recombination Hotspots ◽

Double Strand Dna Breaks ◽

His4 Gene

In a wild-type strain of Saccharomyces cerevisiae, a hotspot for meiotic recombination is located upstream of the HIS4 gene. An insertion of a 49-bp telomeric sequence into the coding region of HIS4 strongly stimulates meiotic recombination and the local formation of meiosis-specific double-strand DNA breaks (DSBs). When strains are constructed in which both hotspots are heterozygous, hotspot activity is substantially less when the hotspots are on the same chromosome than when they are on opposite chromosomes.

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Micronuclear DNA sequences from Tetrahymena do not confer mitotic stability on ARS plasmids in Saccharomyces

Genome ◽

10.1139/g88-116 ◽

1988 ◽

Vol 30 (5) ◽

pp. 690-696 ◽

Cited By ~ 3

Author(s):

Wendy H. Horsfall ◽

Ronald E. Pearlman

Keyword(s):

Saccharomyces Cerevisiae ◽

Dna Sequences ◽

Copy Number ◽

Tetrahymena Thermophila ◽

Assay System ◽

Mitotic Stability ◽

Yeast Saccharomyces Cerevisiae ◽

Genomic Libraries ◽

Ade2 Gene

Genomic libraries containing micronuclear DNA sequences from Tetrahymena thermophila have been constructed in a vector containing ARS1, SUP11, and ura3 sequences from the yeast Saccharomyces cerevisiae. When transformed into a strain of S. cerevisiae carrying a suppressible ochre mutation in the ade2 gene, viable transformants are obtained only if the transforming plasmid is maintained at a copy number of one or two per cell. Mitotic segregation of the plasmid is easily assessed in a colour assay of transformants. Using this assay system, we showed that micronuclear DNA from Tetrahymena does not contain sequences that confer mitotic stability on yeast ARS-containing plasmids; i.e., sequences that function analogously to yeast centromere sequences. One transformant was analyzed that carries Tetrahymena sequences that maintain the copy number of the ARS plasmid at one or two per cell. However, these sequences do not confer mitotic stability on the transformants and they confer a phenotype in this assay similar to that of the REP3 gene of the yeast 2 μm plasmid.Key words: mitotic stability, centromere, Tetrahymena, Saccharomyces.

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DNA sequence analysis of spontaneous mutations in the SUP4-o gene of Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.8.2.978-981.1988 ◽

1988 ◽

Vol 8 (2) ◽

pp. 978-981

Author(s):

C N Giroux ◽

J R Mis ◽

M K Pierce ◽

S E Kohalmi ◽

B A Kunz

Keyword(s):

Saccharomyces Cerevisiae ◽

Sequence Analysis ◽

Transposable Elements ◽

Dna Sequencing ◽

Dna Sequence ◽

Base Pair ◽

Dna Sequence Analysis ◽

Spontaneous Mutations ◽

Yeast Saccharomyces Cerevisiae ◽

Spontaneous Mutagenesis

A collection of 196 spontaneous mutations in the SUP4-o gene of the yeast Saccharomyces cerevisiae was analyzed by DNA sequencing. The classes of mutation identified included all possible types of base-pair substitution, deletions of various lengths, complex alterations involving multiple changes, and insertions of transposable elements. Our findings demonstrate that at least several different mechanisms are responsible for spontaneous mutagenesis in S. cerevisiae.

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DNA SEQUENCES OF FRAMESHIFT AND OTHER MUTATIONS INDUCED BY ICR-170 IN YEAST

Genetics ◽

10.1093/genetics/111.2.233 ◽

1985 ◽

Vol 111 (2) ◽

pp. 233-241

Author(s):

Joachim F Ernst ◽

D Michael Hampsey ◽

Fred Sherman

Keyword(s):

Saccharomyces Cerevisiae ◽

Amino Acid ◽

Sequence Analysis ◽

Genetic Analysis ◽

Dna Sequences ◽

Induced Mutations ◽

Sequence Analyses ◽

Base Pairs ◽

Yeast Saccharomyces Cerevisiae ◽

Frameshift Mutations

ABSTRACT ICR-170-induced mutations in the CYC1 gene of the yeast Saccharomyces cerevisiae were investigated by genetic and DNA sequence analyses. Genetic analysis of 33 cyc1 mutations induced by ICR-170 and sequence analysis of eight representatives demonstrated that over one-third were frameshift mutations that occurred at one site corresponding to amino acid positions 29-30, whereas the remaining mutations were distributed more-or-less randomly, and a few of these were not frameshift mutations. The sequence results indicate that ICR-170 primarily induces G·C additions at sites containing monotonous runs of three G·C base pairs. However, some (see PDF) sites within the CYC1 gene were not mutated by ICR-170. Thus, ICR-170 is a relatively specific mutagen that preferentially acts on certain sites with monotonous runs of G·C base pairs.

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Positive control of sporulation-specific genes by the IME1 and IME2 products in Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.10.5.2104-2110.1990 ◽

1990 ◽

Vol 10 (5) ◽

pp. 2104-2110

Author(s):

A P Mitchell ◽

S E Driscoll ◽

H E Smith

Keyword(s):

Gene Expression ◽

Saccharomyces Cerevisiae ◽

Meiotic Recombination ◽

Positive Control ◽

Spore Formation ◽

Specific Gene ◽

Heterologous Promoter ◽

Yeast Saccharomyces Cerevisiae ◽

Specific Gene Expression ◽

Rapid Induction

In the yeast Saccharomyces cerevisiae, meiosis and spore formation require the induction of sporulation-specific genes. Two genes are thought to activate the sporulation program: IME1 and IME2 (inducer of meiosis). Both genes are induced upon entry into meiosis, and IME1 is required for IME2 expression. We report here that IME1 is essential for expression of four sporulation-specific genes. In contrast, IME2 is not absolutely essential for expression of the sporulation-specific genes, but contributes to their rapid induction. Expression of IME2 from a heterologous promoter permits the expression of these sporulation-specific genes, meiotic recombination, and spore formation in the absence of IME1. We propose that the IME1 and IME2 products can each activate sporulation-specific genes independently. In addition, the IME1 product stimulates sporulation-specific gene expression indirectly through activation of IME2 expression.

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DNA Sequence Analysis of Spontaneous Mutagenesis in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/148.4.1491 ◽

1998 ◽

Vol 148 (4) ◽

pp. 1491-1505 ◽

Cited By ~ 5

Author(s):

Bernard A Kunz ◽

Karthikeyan Ramachandran ◽

Edward J Vonarx

Keyword(s):

Saccharomyces Cerevisiae ◽

Sequence Analysis ◽

Dna Sequencing ◽

Dna Sequence ◽

Budding Yeast ◽

Spontaneous Mutation ◽

Dna Sequence Analysis ◽

Mutation Rates ◽

Yeast Saccharomyces Cerevisiae ◽

Spontaneous Mutagenesis

AbstractTo help elucidate the mechanisms involved in spontaneous mutagenesis, DNA sequencing has been applied to characterize the types of mutation whose rates are increased or decreased in mutator or antimutator strains, respectively. Increased spontaneous mutation rates point to malfunctions in genes that normally act to reduce spontaneous mutation, whereas decreased rates are associated with defects in genes whose products are necessary for spontaneous mutagenesis. In this article, we survey and discuss the mutational specificities conferred by mutator and antimutator genes in the budding yeast Saccharomyces cerevisiae. The implications of selected aspects of the data are considered with respect to the mechanisms of spontaneous mutagenesis.

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