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Is there left-handed DNA at the ends of yeast chromosomes?

R M Walmsley, J W Szostak, T D Petes

    Nature
    |March 3, 1983
    PubMed

    Insights

    Poly(GT) tracts, known for forming Z-DNA, are found in yeast chromosomes. This study reveals these sequences are located at telomeres, chromosome ends, and are added to extrachromosomal DNA in yeast.

    Area of Science:

    • Molecular Biology
    • Genetics
    • Biochemistry

    Background:

    • Alternating copolymer poly(dGdT . dCdA) tracts are found in eukaryotes.
    • These sequences can form left-handed Z-form DNA in vitro.
    • The yeast Saccharomyces cerevisiae possesses numerous poly(GT) tracts.

    Purpose of the Study:

    • To investigate the genomic locations of poly(GT) tracts in yeast.
    • To determine if these tracts are associated with specific chromosomal structures.
    • To explore the role of poly(dGdT . dCdA) in yeast extrachromosomal DNA.

    Main Methods:

    • Genomic analysis in Saccharomyces cerevisiae.
    • Identification and mapping of poly(GT) tracts.
    • Cloning and characterization of Tetrahymena extrachromosomal DNA in yeast.

    Main Results:

    • At least 30 poly(GT) tracts were identified in the yeast genome.
    • A subset of these poly(GT) tracts was found at yeast chromosome telomeres.
    • Poly(dGdT . dCdA) tracts were observed to be added to the ends of Tetrahymena rDNA in yeast.

    Conclusions:

    • Poly(GT) tracts are associated with yeast telomeres.
    • This represents the first reported link between homopolymeric sequences and chromosome structure.
    • The findings suggest a role for these tracts in telomere biology or DNA processing in yeast.

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