Publications by authors named "Megan E Ibos"
Chromosomal sites of RNA polymerase III (Pol III) transcription have been demonstrated to have "extratranscriptional" functions, as the assembled Pol III complex can act as chromatin boundaries or pause sites for replication forks, can alter nucleosome positioning or affect transcription of neighboring genes, and can play a role in sister chromatid cohesion. Several studies have demonstrated that assembled Pol III complexes block the propagation of heterochromatin-mediated gene repression. Here we show that in Saccharomyces cerevisiae tRNA genes (tDNAs) and even partially assembled Pol III complexes containing only the transcription factor TFIIIC can exhibit chromatin boundary functions both as heterochromatin barriers and as insulators to gene activation.
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- A tRNA gene near the HMR locus in yeast (S. cerevisiae) acts as a barrier to prevent the spread of gene silencing from heterochromatin into adjacent regions of chromosome III.
- A genetic screen identified YTA7, a gene with bromodomain and ATPase features, as important for restricting this silencing, while the deletion of RSC2, part of a chromatin-remodeling complex, increased silencing spread.
- The study implies that YTA7 and the tRNA element work independently to limit silencing, indicating that various bromodomain proteins play a role in managing heterochromatin spread at the HMR locus.