Structural characterization of chromosome I size variants from a natural yeast strain.
Many yeast strains isolated from the wild show karyotype instability during vegetative growth, with rearrangement rates of up to 10(-2) chromosomal changes per generation. Physical isolation and analysis of several chromosome I size variants of one of these strains revealed that they differed only in their subtelomeric regions, leaving the central 150 Kb unaltered. Fine mapping of these subtelomeric variable regions revealed gross alterations of two very similar loci, FLO1 and FLO9. These loci are located on the right and left arms, respectively, of chromosome I and encompass internal repetitive DNA sequences. Furthermore, some chromosome I variants lacking the FLO1 locus showed evidence of recombination at a DNA region on their right arm that is enriched in repeated sequences, including Ty LTRs. We propose that repetitive sequences in many subtelomeric regions in S. cerevisiae play a key role in karyotype hypervariability. As these regions encode several membrane-associated proteins, subtelomeric plasticity may allow rapid adaptive changes of the yeast strain to specific substrates. This pattern of semi-conservative chromosomal rearrangement may have profound implications, both in terms of evolution of wild strains and for biotechnological processes.
Carro
David
D
Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Jordi Girona 18, 08034 Barcelona, Spain.
García-Martinez
José
J
Pérez-Ortín
José E
JE
Piña
Benjamin
B
D015139:Blotting, Southern; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D019143:Evolution, Molecular; D014644:Genetic Variation / Q000235:genetics / Q000502:physiology; D007621:Karyotyping; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic / Q000235:genetics / Q000502:physiology; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D017422:Sequence Analysis, DNA; D016615:Telomere / Q000235:genetics / Q000502:physiology
D004271:DNA, Fungal