A<i>buff</i>spore colour mutant in<i>Sordaria brevicollis</i>showing high-frequency conversion

Macdonald, M. V.; Whitehouse, H. L. K.

doi:10.1017/s0016672300019352

Cited by 49 publications

(22 citation statements)

References 26 publications

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“…The 8-base-pair (bp) Chi sequence in Escherichia coli is the most fully characterized recombination hotspot, shown to increase recombination in bacteriophage lambda and E. coli DNA via the RecA-RecBCD pathway (reviewed in reference 34). Recombination hotspots have also been described in fungi (12,25) and in mammalian cells (37; W. P. Wahls, L. J. Wallace, and P. D. Moore, Cell, in press).A short fragment of mammalian DNA from the human ,Bglobin gene cluster, MG-1 (29), promotes unusual recombination events during yeast meiosis (41). Molecular evidence indicates that the DNA sequence responsible is an 80-bp stretch of the simple repeating dinucleotide polydeoxythymidylic-guanylic polydeoxyadenylic-cytidylic acid, abbreviated hereafter as d(TG)n.…”

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The Z-DNA motif d(TG)30 promotes reception of information during gene conversion events while stimulating homologous recombination in human cells in culture.

Wahls¹,

Wallace²,

Moore³

1990

Mol. Cell. Biol.

139

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Tracts of the alternating dinucleotide polydeoxythymidylic-guanylic [d(TG)] polydeoxyadenylic-cytidylic acid [d(AC)], present throughout the human genome, are capable of readily forming left-handed Z-DNA in vitro. We have analyzed the effects of the Z-DNA motif d(TG)30 upon homologous recombination between two nonreplicating plasmid substrates cotransfected into human cells in culture. In this study, the sequence d(TG)30 is shown to stimulate homologous recombination up to 20-fold. Enhancement is specific to the Z-DNA motif; a control DNA fragment of similar size does not alter the recombination frequency. The stimulation of recombination is observed at a distance (237 to 1,269 base pairs away from the Z-DNA motif) and involves both gene conversion and reciprocal exchange events. Maximum stimulation is observed when the sequence is present in both substrates, but it is capable of stimulating when present in only one substrate. Analysis of recombination products indicates that the Z-DNA motif increases the frequency and alters the distribution of multiple, unselected recombination events. Specifically designed crosses indicate that the substrate containing the Z-DNA motif preferentially acts as the recipient of genetic information during gene conversion events. Models describing how left-handed Z-DNA sequences might promote the initiation of homologous recombination are presented.Homologous recombination is the process of exchange of genetic information between stretches of DNA containing sequence similarity. Although the degree of recombination is generally proportional to the length of homology, there are regions of DNA in which the rate of exchange is nonlinear with respect to distance, resulting in disparity between genetic and physical maps. The sequences responsible for this disparity, called "recombination hotspots," increase the rate of genetic exchange between homologous DNA molecules. The 8-base-pair (bp) Chi sequence in Escherichia coli is the most fully characterized recombination hotspot, shown to increase recombination in bacteriophage lambda and E. coli DNA via the RecA-RecBCD pathway (reviewed in reference 34). Recombination hotspots have also been described in fungi (12,25) and in mammalian cells (37; W. P. Wahls, L. J. Wallace, and P. D. Moore, Cell, in press).A short fragment of mammalian DNA from the human ,Bglobin gene cluster, MG-1 (29), promotes unusual recombination events during yeast meiosis (41). Molecular evidence indicates that the DNA sequence responsible is an 80-bp stretch of the simple repeating dinucleotide polydeoxythymidylic-guanylic polydeoxyadenylic-cytidylic acid, abbreviated hereafter as d(TG)n.The repeating dinucleotide d(TG)" is not detectable in the genomes of eubacteria, archaebacteria, or mitochondria (11) but is ubiquitously present in eucaryotic chromosomes (13,29,40). It is estimated that there are on the order of 105 copies of this dinucleotide repeat, each approximately 10 to 50 bp in length, scattered throughout the mammalian genome. A striking feature of these r...

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confidence: 98%

mentioning

confidence: 99%

The Z-DNA motif d(TG)30 promotes reception of information during gene conversion events while stimulating homologous recombination in human cells in culture.

Wahls¹,

Wallace²,

Moore³

1990

Mol. Cell. Biol.

139

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“…Mutations or strain differences identifying hot spots were originally found in fungi (Angel et al 1970;Gutz 1971;MacDonald and Whitehouse 1979) and have been subsequently found in a variety of organisms from bacteriophages (Lain et al 1974~ Stahl et al 1975) to humans (Wahls et al 1990a). Known recombination hot spots stimulate recombination up to 30-fold and exert their effects within a few tens of kilobase pairs.…”

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A heteromeric protein that binds to a meiotic homologous recombination hot spot: correlation of binding and hot spot activity.

Wahls¹,

Smith²

1994

Genes Dev.

107

179

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Homologous recombination hot spots are DNA sites that increase the frequency of recombination in their vicinity. The M26 allele of the ade6 gene in Schizosaccharomyces pombe is the first meiotic hot spot with an identified unique nucleotide sequence. We have purified 40,000-fold a heteromeric protein, containing polypeptides Mtsl (70 kD) and Mts2 (28 kD1, that binds to the M26 site. Binding in vitro strictly correlates with hot spot activity in vivo for numerous single base pair substitutions in the vicinity of the M26 site, indicating that Mtsl/Mts2 activates the M26 site and promotes a rate-limiting step of meiotic recombination. These and other data suggest that homologous recombination may be regulated primarily by discrete DNA sites and proteins that interact with those sites.

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“…Several meiotic recombination hot spots have been identified, including the M26 mutation of ade6 in Schizosaccharomyces pombe (8), the YS17 mutation of the buff spore color locus in Sordaria brevicolis (18), and the cog' mutation in Neurospora crassa (1). In addition, the HOT] gene in the rRNA gene cluster in Saccharomyces cerevisiae functions in cis to stimulate mitotic recombination (13).…”

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Characterization of a centromere-linked recombination hot spot in Saccharomyces cerevisiae.

Neitz¹,

Carbon²

1987

Mol. Cell. Biol.

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A 1.5-kilobase-pair SalI-HindIll (SH) Recombination hot spots are DNA sequences that stimulate genetic exchange in adjoining DNA segments; such hot spots have been identified in both procaryotes and eucaryotes. Several meiotic recombination hot spots have been identified, including the M26 mutation of ade6 in Schizosaccharomyces pombe (8), the YS17 mutation of the buff spore color locus in Sordaria brevicolis (18), and the cog' mutation in Neurospora crassa (1). In addition, the HOT] gene in the rRNA gene cluster in Saccharomyces cerevisiae functions in cis to stimulate mitotic recombination (13). Available evidence suggests that these elemnents function by generating recognition sites for recombination endonucleases or by increasing the accessibility of flanking sequences to recombination enzymes.Recently, it has been postulated that in S. cerevisiae some meiotic and mitotic recombination events occur via a double-strand-gap repair mechanism (33). According to this model, double-strand breaks are introduced into DNA and then enlarged to double-strand gaps. Crossing over and gene conversion occur during gap repair.The general phenomenon of crossing over in the region of centromeres (CEN) has been of particular interest to geneticists because distances between markers in these regions are often disparate when cytological and genetic maps are compared (21, 27). In addition, mitotic and meiotic maps often disagree owing to the fact that the proportion of mitotic exchange events in some CEN-proximal regions is much higher than the relative frequency of meiotic exchange events in these regions (19,21,27 stimulate mitotic exchange in the vicinity of some centromeres. The results of experiments described here suggest that such an element occurs immediately adjacent to CEN14 of S. cerevisiae. In this paper, we present a characterization of a mitotic recombination-enhancing activity contained within a 1.5-kilobase-pair (kb) SaII-HindIII restriction fragment (SH fragment) originating from the centromere region of yeast chromosome XIV. The presence of SH DNA on YRp7 plasmids stimulates homologous genetic exchange between yeast genomic sequences and those present on the plasmid. In all recombinants characterized, exchange occurred in yeast sequences present on the plasmid adjacent to the SH DNA. Hybridization analyses revealed that SH-containing plasmids are present in both linear and circular forms in yeasts and that linear forms are generated by cleavage at specific sites. Control plasmids that lack SH DNA are also present as circular and linear forms in S. cerevisiae; however, they appear to be linearized by cleavage at random sites. Based on these observations, it is proposed that (i) sequences contained within the SH fragment provide hot spot function and that (ii) SH-stimulated recombination occurs via a mechanism similar to double-strand-gap repair. MATERIALS AND METHODSStrains, media, and enzymes. Escherichia coli JA300 (thrA leuB6 hsdR hsdM trpCi 17 strR) was used for transformations and preparation of plasmid DN...

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Abuffspore colour mutant inSordaria brevicollisshowing high-frequency conversion

Cited by 49 publications

References 26 publications

The Z-DNA motif d(TG)30 promotes reception of information during gene conversion events while stimulating homologous recombination in human cells in culture.

The Z-DNA motif d(TG)30 promotes reception of information during gene conversion events while stimulating homologous recombination in human cells in culture.

A heteromeric protein that binds to a meiotic homologous recombination hot spot: correlation of binding and hot spot activity.

Characterization of a centromere-linked recombination hot spot in Saccharomyces cerevisiae.

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