Recovery of a function involving gene duplication by retroposition in Saccharomyces cerevisiae.
The duplication of DNA sequences contributes to genomic plasticity and is known to be one of the key factors responsible for evolution. The mechanisms underlying these rare events, which have been frequently mentioned by authors performing genomic analysis, have not yet been completely elucidated. These mechanisms were approached here in the yeast Saccharomyces cerevisiae, using a positive selection screen based on a particular mutated allele of the URA2 gene. Spontaneous revertants containing a duplication of the terminal part of the URA2 gene were selected and analyzed. Some important features of the duplicated regions, such as their chromosome location, size, and insertion sites, were characterized. The events selected correspond to a single inter- or intrachromosomal gene duplication process. The duplicated ATCase sequence is generally punctuated by a poly(A) tract and is always located in Ty1 sequences. In addition, the activation of a Ty1 transcription process increased the frequency of the duplication events. All in all, these data suggest that the duplication mechanism involves the reverse transcription of mRNA and the subsequent integration of the cDNA into a Ty1 area. The Ty1 elements and the retrotransposon-encoded function are key factors contributing to chromosomal reshaping. The genomic rearrangements described constitute experimental evidence for the recovery of a function involving duplication by retroposition.
Schacherer
Joseph
J
Laboratoire de Microbiologie et de Génétique FRE 2326, Université Louis-Pasteur/CNRS, Strasbourg 67083, France.
Tourrette
Yves
Y
Souciet
Jean-Luc
JL
Potier
Serge
S
De Montigny
Jacky
J
D024509:3' Flanking Region / Q000235:genetics; D024506:5' Flanking Region / Q000235:genetics; D001221:Aspartate Carbamoyltransferase / Q000235:genetics / Q000502:physiology; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000235:genetics / Q000502:physiology; D002874:Chromosome Mapping / Q000379:methods; D015825:Chromosomes, Fungal / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D020440:Gene Duplication; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal / Q000235:genetics / Q000502:physiology; D009097:Multienzyme Complexes / Q000235:genetics / Q000502:physiology; D011995:Recombination, Genetic / Q000235:genetics / Q000502:physiology; D018626:Retroelements / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology; D017422:Sequence Analysis, DNA / Q000379:methods; D014158:Transcription, Genetic / Q000235:genetics
D004271:DNA, Fungal; D009097:Multienzyme Complexes; D018626:Retroelements; D029701:Saccharomyces cerevisiae Proteins; C110837:URA2 protein, S cerevisiae; D001221:Aspartate Carbamoyltransferase; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)