scholarly journals Tetrad analysis shows that gene conversion is the major mechanism involved in mutation at the human minisatellite MS1 integrated in Saccharomyces cerevisiae

2000 ◽  
Vol 75 (1) ◽  
pp. 1-12 ◽  
Author(s):  
INGRID BERG ◽  
HÅKAN CEDERBERG ◽  
ULF RANNUG
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Human Genome ◽  
Dna Sequences ◽  
Hot Spot ◽  
Tetrad Analysis ◽  
Strand Breaks ◽  
Major Mechanism ◽  
Marker Conversion ◽  
Repeat Units ◽  
Chromosome Iii

Minisatellites are arrays of tandemly repeated DNA sequences which occur at thousands of locations in the human genome. They are frequently hypervariable with respect to allele length as a result of high rates of complex and incompletely understood recombination-based germline mutation events that alter the repeat copy number. MS1 is one of the most variable minisatellites so far isolated from the human genome. We have integrated MS1, flanked by synthetic markers, in the vicinity of a hot spot for meiotic double-strand breaks upstream of the LEU2 locus in chromosome III of Saccharomyces cerevisiae. Here we present the first tetrad analysis of mutations at a human minisatellite locus. The data showed that mutant alleles occur as single mutants in one of the spores in a tetrad, also when the mutant structure was the result of a combination of intra- and inter-allelic rearrangements. The conversional transfer of repeat units from one allele to the other was associated with flanking marker conversion which always involved the same flank of the minisatellite. The results demonstrate that conversion is the predominant mechanism by which minisatellite alleles mutate to new lengths, and also support the assumption that cis-acting elements are involved in the regulation of the mutational process in humans.

Effects of excess centromeres and excess telomeres on chromosome loss rates

1991 ◽  
Vol 11 (6) ◽  
pp. 2919-2928
Author(s):  
K W Runge ◽  
R J Wellinger ◽  
V A Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Sequences ◽  
Fluctuation Analysis ◽  
Chromosome Stability ◽  
Chromosome Loss ◽  
Division Iii ◽  
Daughter Cells ◽  
Chromosome Iii ◽  
Linear Chromosomes

The linear chromosomes of eukaryotes contain specialized structures to ensure their faithful replication and segregation to daughter cells. Two of these structures, centromeres and telomeres, are limited, respectively, to one and two copies per chromosome. It is possible that the proteins that interact with centromere and telomere DNA sequences are present in limiting amounts and could be competed away from the chromosomal copies of these elements by additional copies introduced on plasmids. We have introduced excess centromeres and telomeres into Saccharomyces cerevisiae and quantitated their effects on the rates of loss of chromosome III and chromosome VII by fluctuation analysis. We show that (i) 600 new telomeres have no effect on chromosome loss; (ii) an average of 25 extra centromere DNA sequences increase the rate of chromosome III loss from 0.4 x 10(-4) events per cell division to 1.3 x 10(-3) events per cell division; (iii) centromere DNA (CEN) sequences on circular vectors destabilize chromosomes more effectively than do CEN sequences on 15-kb linear vectors, and transcribed CEN sequences have no effect on chromosome stability. We discuss the different effects of extra centromere and telomere DNA sequences on chromosome stability in terms of how the cell recognizes these two chromosomal structures.

scholarly journals RAD1 Controls the Meiotic Expansion of the Human HRAS1 Minisatellite in Saccharomyces cerevisiae

2002 ◽  
Vol 22 (3) ◽  
pp. 953-964 ◽  
Author(s):  
Peter A. Jauert ◽  
Sharon N. Edmiston ◽  
Kathleen Conway ◽  
David T. Kirkpatrick
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Repetitive Dna ◽  
Hot Spot ◽  
Repeat Unit ◽  
Unit Length ◽  
Wild Type ◽  
Strand Breaks ◽  
Tract Length ◽  
Sequence Composition ◽  
Repeat Unit Length

ABSTRACT Minisatellite DNA is repetitive DNA with a repeat unit length from 15 to 100 bp. While stable during mitosis, it destabilizes during meiosis, altering both in length and in sequence composition. The basis for this instability is unknown. To investigate the factors controlling minisatellite stability, a minisatellite sequence 3′ of the human HRAS1 gene was introduced into the Saccharomyces cerevisiae genome, replacing the wild-type HIS4 promoter. The minisatellite tract exhibited the same phenotypes in yeast that it exhibited in mammalian systems. The insertion stimulated transcription of the HIS4 gene; mRNA production was detected at levels above those seen with the wild-type promoter. The insertion stimulated meiotic recombination and created a hot spot for initiation of double-strand breaks during meiosis in the regions immediately flanking the repetitive DNA. The tract length altered at a high frequency during meiosis, and both expansions and contractions in length were detected. Tract expansion, but not contraction, was controlled by the product of the RAD1 gene. RAD1 is the first gene identified that controls specifically the expansion of minisatellite tracts. A model for tract length alteration based on these results is presented.

scholarly journals Effects of excess centromeres and excess telomeres on chromosome loss rates.

1991 ◽  
Vol 11 (6) ◽  
pp. 2919-2928 ◽  
Author(s):  
K W Runge ◽  
R J Wellinger ◽  
V A Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Sequences ◽  
Fluctuation Analysis ◽  
Chromosome Stability ◽  
Chromosome Loss ◽  
Division Iii ◽  
Daughter Cells ◽  
Chromosome Iii ◽  
Linear Chromosomes

The linear chromosomes of eukaryotes contain specialized structures to ensure their faithful replication and segregation to daughter cells. Two of these structures, centromeres and telomeres, are limited, respectively, to one and two copies per chromosome. It is possible that the proteins that interact with centromere and telomere DNA sequences are present in limiting amounts and could be competed away from the chromosomal copies of these elements by additional copies introduced on plasmids. We have introduced excess centromeres and telomeres into Saccharomyces cerevisiae and quantitated their effects on the rates of loss of chromosome III and chromosome VII by fluctuation analysis. We show that (i) 600 new telomeres have no effect on chromosome loss; (ii) an average of 25 extra centromere DNA sequences increase the rate of chromosome III loss from 0.4 x 10(-4) events per cell division to 1.3 x 10(-3) events per cell division; (iii) centromere DNA (CEN) sequences on circular vectors destabilize chromosomes more effectively than do CEN sequences on 15-kb linear vectors, and transcribed CEN sequences have no effect on chromosome stability. We discuss the different effects of extra centromere and telomere DNA sequences on chromosome stability in terms of how the cell recognizes these two chromosomal structures.

scholarly journals Double strand breaks at the HIS2 recombination hot spot in Saccharomyces cerevisiae

1996 ◽  
Vol 93 (23) ◽  
pp. 13054-13059 ◽  
Author(s):  
S. A. Bullard ◽  
S. Kim ◽  
A. M. Galbraith ◽  
R. E. Malone
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hot Spot ◽  
Double Strand Breaks ◽  
Strand Breaks

scholarly journals A short chromosomal region with major roles in yeast chromosome III meiotic disjunction, recombination and double strand breaks.

Genetics ◽  
1993 ◽  
Vol 133 (2) ◽  
pp. 159-169 ◽  
Author(s):  
M Goldway ◽  
A Sherman ◽  
D Zenvirth ◽  
T Arbel ◽  
G Simchen
Keyword(s):  
Genomic Library ◽  
Hot Spot ◽  
Strand Break ◽  
Multicopy Plasmid ◽  
Strand Breaks ◽  
Cis Acting ◽  
Meiotic Nondisjunction ◽  
Chromosome Iii ◽  
The Right ◽  
Mutant Cells

Abstract A multicopy plasmid was isolated from a yeast genomic library, whose presence resulted in a twofold increase in meiotic nondisjunction of chromosome III. The plasmid contains a 7.5-kb insert from the middle of the right arm of chromosome III, including the gene THR4. Using chromosomal fragments derived from chromosome III, we determined that the cloned region caused a significant, specific, cis-acting increase in chromosome III nondisjunction in the first meiotic division. The plasmid containing this segment exhibited high spontaneous meiotic integration into chromosome III (in 2.4% of the normal meiotic divisions) and a sixfold increase (15.5%) in integration in nondisjunctant meioses. Genetic analysis of the cloned region revealed that it contains a "hot spot" for meiotic recombination. In DNA of rad50S mutant cells, a strong meiosis-induced double strand break (DSB) signal was detected in this region. We discuss the possible relationships between meiosis-induced DSBs, recombination and chromosome disjunction, and propose that recombinational hot spots may be "pairing sites" for homologous chromosomes in meiosis.

scholarly journals The essential helicase gene RAD3 suppresses short-sequence recombination in Saccharomyces cerevisiae.

1995 ◽  
Vol 15 (8) ◽  
pp. 3998-4008 ◽  
Author(s):  
A M Bailis ◽  
S Maines ◽  
M T Negritto
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Sequences ◽  
Physical Stability ◽  
Strand Break ◽  
Gene Replacement ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Sequences ◽  
Helicase Gene ◽  
Mutant Cells

We have isolated an allele of the essential DNA repair and transcription gene RAD3 that relaxes the restriction against recombination between short DNA sequences in Saccharomyces cerevisiae. Double-strand break repair and gene replacement events requiring recombination between short identical or mismatched sequences were stimulated in the rad3-G595R mutant cells. We also observed an increase in the physical stability of double-strand breaks in the rad3-G595R mutant cells. These results suggest that the RAD3 gene suppresses recombination involving short homologous sequences by promoting the degradation of the ends of broken DNA molecules.

scholarly journals A replication map of a 61-kb circular derivative of Saccharomyces cerevisiae chromosome III.

1992 ◽  
Vol 3 (9) ◽  
pp. 999-1013 ◽  
Author(s):  
S A Greenfeder ◽  
C S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Sequences ◽  
Ring Chromosome ◽  
Replication Initiation ◽  
Cis Acting ◽  
Dna Replication Initiation ◽  
Ars Elements ◽  
Highly Active ◽  
Origin Function ◽  
Chromosome Iii

Using two-dimensional agarose gel electrophoresis, we determined the replication map of a 61-kb circular derivative of Saccharomyces cerevisiae chromosome III. The three sites of DNA replication initiation on the ring chromosome are specific and coincide with ARS elements. The three origins are active to different degrees; two are used > 90% of the time, whereas the third is used only 10-20% of the time. The specificity of these origins is shown by the fact that only ARS elements were competent for origin function, and deletion of one of the ARS elements removed the corresponding replication origin. The activity of the least active origin was not increased by deletion of the nearby highly active origin, demonstrating that the highly active origin does not repress function of the relatively inactive origin. Replication termination on the ring chromosome does not occur at specific sites but rather occurs over stretches of DNA ranging from 3 to 10 kb. A new region of termination was created by altering the sites of initiation. The position of the new termination site indicates that termination is not controlled by specific cis-acting DNA sequences, but rather that replication termination is determined primarily by the positions at which replication initiates. In addition, two sites on the ring chromosome were found to slow the progression of replication forks through the molecule: one is at the centromere and one at the 3' end of a yeast transposable element.

scholarly journals Meiosis-specific double-strand DNA breaks at the HIS4 recombination hot spot in the yeast Saccharomyces cerevisiae: control in cis and trans.

1995 ◽  
Vol 15 (3) ◽  
pp. 1679-1688 ◽  
Author(s):  
Q Fan ◽  
F Xu ◽  
T D Petes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hot Spot ◽  
Wild Type ◽  
Dna Breaks ◽  
Yeast Saccharomyces Cerevisiae ◽  
Double Strand Dna Breaks ◽  
Spot Activity ◽  
Chromosome Iii ◽  
High Level ◽  
Double Strand Dna

The region of Saccharomyces cerevisiae chromosome III located between the 5' end of the HIS4 gene and the 3' end of the adjacent BIK1 gene has a very high level of meiotic recombination. In wild-type strains, a meiosis-specific double-strand DNA break occurs in the hot spot region. This break is absent in strains in which the transcription factors Rap1p, Bas1p, and Bas2p cannot bind to the region upstream of HIS4. In strains with levels of recombination that are higher than those of the wild type, the break is found at elevated levels. The linear relationship between hot spot activity and the frequency of double-strand DNA breaks suggests that these lesions are responsible for initiating recombination at the HIS4 recombination hot spot.

DNA methylation in satellite repeats disorders

2019 ◽  
Vol 63 (6) ◽  
pp. 757-771 ◽  
Author(s):  
Claire Francastel ◽  
Frédérique Magdinier
Keyword(s):  
Dna Methylation ◽  
Human Genome ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Satellite Repeats ◽  
Tremendous Progress ◽  
Genes Encoding ◽  
Dna Elements ◽  
Near Future

Abstract Despite the tremendous progress made in recent years in assembling the human genome, tandemly repeated DNA elements remain poorly characterized. These sequences account for the vast majority of methylated sites in the human genome and their methylated state is necessary for this repetitive DNA to function properly and to maintain genome integrity. Furthermore, recent advances highlight the emerging role of these sequences in regulating the functions of the human genome and its variability during evolution, among individuals, or in disease susceptibility. In addition, a number of inherited rare diseases are directly linked to the alteration of some of these repetitive DNA sequences, either through changes in the organization or size of the tandem repeat arrays or through mutations in genes encoding chromatin modifiers involved in the epigenetic regulation of these elements. Although largely overlooked so far in the functional annotation of the human genome, satellite elements play key roles in its architectural and topological organization. This includes functions as boundary elements delimitating functional domains or assembly of repressive nuclear compartments, with local or distal impact on gene expression. Thus, the consideration of satellite repeats organization and their associated epigenetic landmarks, including DNA methylation (DNAme), will become unavoidable in the near future to fully decipher human phenotypes and associated diseases.

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