The Saccharomyces cerevisiae RDN1 locus is sequestered from interchromosomal meiotic ectopic recombination in a SIR2-dependent manner.

Meiotic ectopic recombination occurs at similar frequencies among many sites in the yeast genome, suggesting that all loci are similarly accessible to homology searching. In contrast, we found that his3 sequences integrated in the RDN1 (rDNA) locus were unusually poor participants in meiotic recombination with his3 sequences at other sites. We show that the low rate of meiotic ectopic recombination resulted from the poor ability of RDN1::his3 to act as a donor sequence. SIR2 partially repressed interchromosomal meiotic ectopic recombination at RDN1, consistent with its role in regulating recombination, gene expression, and retrotransposition within RDN1. We propose that RDN1 is physically sequestered from meiotic homology searching mechanisms.