Spontaneous deletions and reciprocal translocations in Saccharomyces cerevisiae: influence of ploidy.
Studying spontaneous chromosomal rearrangements throws light on the rules underlying the genome reshaping events occurring in eukaryotic cells, which are part of the evolutionary process. In Saccharomyces cerevisiae, translocation and deletion processes have been frequently described in haploids, but little is known so far about these processes at the diploid level. Here we investigated the nature and the frequency of the chromosomal rearrangements occurring at this ploidy level. Using a positive selection screen based on a particular mutated allele of the URA2 gene, spontaneous diploid revertants were selected and analysed. Surprisingly, the diploid state was found to be correlated with a decrease in chromosome rearrangement frequency, along with an increase in the complexity of the rearrangements occurring in the target gene. The presence of short DNA tandem repeat sequences seems to be a key requirement for deletion and reciprocal translocation processes to occur in diploids. After discussing the differences between the haploid and diploid levels, some mechanisms possibly involved in chromosome shortening and arm exchange are suggested.
Tourrette
Yves
Y
UMR 7156 Université Louis-Pasteur/CNRS, Génétique Moléculaire, Génomique, Microbiologie, Département Microorganismes, Génomes, Environnement, Strasbourg, France. y.tourrette@ibmc.u-strasbg.fr
Schacherer
Joseph
J
Fritsch
Emilie
E
Potier
Serge
S
Souciet
Jean-Luc
JL
de Montigny
Jacky
J
D001221:Aspartate Carbamoyltransferase / Q000235:genetics; D001483:Base Sequence; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000235:genetics; D015825:Chromosomes, Fungal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004171:Diploidy; D017353:Gene Deletion; D015321:Gene Rearrangement; D005800:Genes, Fungal; D052836:Heterotrophic Processes; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D011003:Ploidies; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D014178:Translocation, Genetic; D014498:Uracil / Q000378:metabolism
D004268:DNA-Binding Proteins; D009097:Multienzyme Complexes; C441270:NEJ1 protein, S cerevisiae; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C110837:URA2 protein, S cerevisiae; D014498:Uracil; D001221:Aspartate Carbamoyltransferase; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)