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Position‐dependent instability of ribosomal DNA repeats (736.1)
Author(s) -
Hochwagen Andreas,
Wang Danni,
Mansisidor Andres
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.736.1
Subject(s) - biology , homologous recombination , genetics , ribosomal dna , tandem repeat , heterochromatin , genome instability , direct repeat , repeated sequence , epigenetics , gene conversion , genome , gene , dna , chromosome , dna damage , phylogenetics
Repetitive DNA arrays are ubiquitous in eukaryotic genomes and represent a special challenge for genome integrity because of the risk of non‐allelic recombination. We used unique sequence tags marking individual repeats in the tandem ribosomal DNA (rDNA) array of budding yeast to determine the likelihood of non‐allelic recombination throughout the array. We found that rDNA repeat stability during meiotic recombination is strongly dependent on relative repeat position, with repeats near the rDNA border being more susceptible to meiotic DNA double‐strand breaks (DSBs) and thus non‐allelic recombination. The DSB position effect is promoted by rDNA heterochromatin and suppressed by the origin recognition complex component Orc1. Border‐dependent position effects in the rDNA also occur at the level of reporter gene expression in vegetative cells, suggesting that such effects are a reflection of a general feature of rDNA structure. Our results indicate that, despite their identity at the sequence level, rDNA repeats are functionally far from uniform. Position‐dependent epigenetic regulation may provide an opportunity to balance gene expression against the inherent instability of large repetitive DNA arrays.