Fine Chromatin-Driven Mechanism of Transcription Interference by Antisense Noncoding Transcription

Abstract

Summary: Eukaryotic genomes are almost entirely transcribed by RNA polymerase II. Consequently, the transcription of long noncoding RNAs often overlaps with coding gene promoters, triggering potential gene repression through a poorly characterized mechanism of transcription interference. Here, we propose a comprehensive model of chromatin-based transcription interference in Saccharomyces cerevisiae (S. cerevisiae). By using a noncoding transcription-inducible strain, we analyze the relationship between antisense elongation and coding sense repression, nucleosome occupancy, and transcription-associated histone modifications using near-base pair resolution techniques. We show that antisense noncoding transcription leads to the deacetylation of a subpopulation of −1/+1 nucleosomes associated with increased H3K36me3. Reduced acetylation results in the decreased binding of the RSC chromatin remodeler at −1/+1 nucleosomes and subsequent sliding into the nucleosome-depleted region hindering pre-initiation complex association. Finally, we extend our model by showing that natural antisense noncoding transcription significantly represses ∼20% of S. cerevisiae genes through this chromatin-based transcription interference mechanism.

Keywords

• noncoding transcription
• antisense
• nucleosomes
• histone modifications
• nucleosome-depleted regions
• chromatin remodeler