Internal tracts of telomeric DNA act as silencers in Saccharomyces cerevisiae

Telomeric position effect (TPE) refers to the ability of telomeres to repress the transcription of genes in their vicinity. Internal stretches of C_1-3A DNA, the sequence found at Saccharomyces telomeres, also repressed transcription of nearby genes. This repression, hereafter called C_1-3A- based silencing, was observed at several chromosomal loci, including on a circular chromosome. The magnitude of C_1-3A-based silencing was increased by both proximity to a telomere and increased length of the C_1-3A tracts. C_1-3A-based silencing was affected by many of the same genes and conditions that influence TPE and acted in an orientation-independent manner. Thus, in yeast, an expanded array of a simple repetitive DNA, C_1-3A, is sufficient to promote the assembly of a transcriptionally silent chromosomal domain.