The fail-safe mechanism of post-transcriptional silencing of unspliced HAC1 mRNA
- University of California, San Francisco, United States
Abstract
HAC1 encodes a transcription factor that is the central effector of the unfolded protein response (UPR) in budding yeast. When the UPR is inactive, HAC1 mRNA is stored as an unspliced isoform in the cytoplasm and no Hac1 protein is detectable. Intron removal is both necessary and sufficient to relieve the post-transcriptional silencing of HAC1 mRNA, yet the precise mechanism by which the intron prevents Hac1 protein accumulation has remained elusive. Here, we show that a combination of inhibited translation initiation and accelerated protein degradation-both dependent on the intron-prevents the accumulation of Hac1 protein when the UPR is inactive. Functionally, both components of this fail-safe silencing mechanism are required to prevent ectopic production of Hac1 protein and concomitant activation of the UPR. Our results provide a mechanistic understanding of HAC1 regulation and reveal a novel strategy for complete post-transcriptional silencing of a cytoplasmic mRNA.
Data availability
-
Whole-genome sequencing of spontaneous mutantsPublicly available at the NCBI Sequence Read Archive (accession no: SRP081128).
-
Data from: Improved Ribosome-Footprint and mRNA Measurements Provide Insights into Dynamics and Regulation of Yeast TranslationPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE75897).
Article and author information
Author details
Funding
NIH Office of the Director (DP5OD017895)
- Rachael Di Santo
- Soufiane Aboulhouda
- David E Weinberg
UCSF Program for Breakthrough Biomedical Research
- Rachael Di Santo
- Soufiane Aboulhouda
- David E Weinberg
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2016, Di Santo et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 3,861
- views
-
- 598
- downloads
-
- 35
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
The fail-safe mechanism of post-transcriptional silencing of unspliced HAC1 mRNA
eLife 5:e20069.
https://doi.org/10.7554/eLife.20069
Further reading
-
- Chromosomes and Gene Expression
The association between late replication timing and low transcription rates in eukaryotic heterochromatin is well known, yet the specific mechanisms underlying this link remain uncertain. In Saccharomyces cerevisiae, the histone deacetylase Sir2 is required for both transcriptional silencing and late replication at the repetitive ribosomal DNA (rDNA) arrays. We have previously reported that in the absence of SIR2, a de-repressed RNA PolII repositions MCM replicative helicases from their loading site at the ribosomal origin, where they abut well-positioned, high-occupancy nucleosomes, to an adjacent region with lower nucleosome occupancy. By developing a method that can distinguish activation of closely spaced MCM complexes, here we show that the displaced MCMs at rDNA origins have increased firing propensity compared to the nondisplaced MCMs. Furthermore, we found that both activation of the repositioned MCMs and low occupancy of the adjacent nucleosomes critically depend on the chromatin remodeling activity of FUN30. Our study elucidates the mechanism by which Sir2 delays replication timing, and it demonstrates, for the first time, that activation of a specific replication origin in vivo relies on the nucleosome context shaped by a single chromatin remodeler.
-
- Chromosomes and Gene Expression
Specialized magnetic beads that bind target proteins to a cryogenic electron microscopy grid make it possible to study the structure of protein complexes from dilute samples.
