Abstract
Recently, much evidence has been brought forth into the scientific community supporting the idea that RNA Polymerase III transcribed regions of DNA may serve as chromosomal landmarks for silencing. Transfer RNA genes are known to involve themselves in several extra-transcriptional functions within the chromosome, including the pausing of replication forks, Ty element integration, tRNA position effects (repression of neighboring genes), acting as a barrier to the spread of heterochromatin, and over-riding nuclosome positioning sequences. Our results suggest that many tRNA genes may serve these functions as well as exhibiting behavior similar to metazoan insulators. Also, ETC (Extra TFIIIC) sites within Saccharomyces cerevisiae, which bind only TFIIIC may also act as barriers or insulators. Our results support the idea that extra-transcriptional functions of RNA Polymerase III factors may be widespread and important contributors to genome biology.
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