Three distinct mechanisms of long-distance modulation of gene expression in yeast

• Published in: PLoS genetics 2017-04, Vol.13 (4), p.e1006736-e1006736
• Main Authors: Du, Manyu, Zhang, Qian, Bai, Lu
• Format: Article
• Language: English
• Subjects: Acids; Antibodies; Assaying; Basic-Leucine Zipper Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - metabolism; Bidirectional; Biochemistry; Biology and Life Sciences; Biosynthesis; Cancer; Cell proliferation; Chromatin; Chromatin - genetics; Chromosomes; Chromosomes, Fungal - genetics; Colleges & universities; Conformation; Data processing; Environmental stress; Eukaryotes; F-Box Proteins - genetics; F-Box Proteins - metabolism; Gene disruption; Gene expression; Gene Expression Regulation, Fungal; Gene loci; Gene regulation; Gene silencing; Genes, Reporter; Genetic aspects; Genome, Fungal; Genomes; Homology; Information systems; Long distance; Molecular biology; Nuclei; Nucleic acids; Nucleotide sequence; Physiological aspects; Polymerase chain reaction; Promoter Regions, Genetic; Promoters; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Silent Information Regulator Proteins, Saccharomyces cerevisiae - genetics; Silent Information Regulator Proteins, Saccharomyces cerevisiae - metabolism; Sirtuin 2 - genetics; Sirtuin 2 - metabolism; Statistical analysis; Tata box; Transcription, Genetic; Ubiquitin-Protein Ligase Complexes - genetics; Ubiquitin-Protein Ligase Complexes - metabolism; Upgrading; Upstream; Upstream activating sequences; Yeasts (Fungi)
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1006736

Recent Hi-C measurements have revealed numerous intra- and inter-chromosomal interactions in various eukaryotic cells. To what extent these interactions regulate gene expression is not clear. This question is particularly intriguing in budding yeast because it has extensive long-distance chromosomal interactions but few cases of gene regulation over-a-distance. Here, we developed a medium-throughput assay to screen for functional long-distance interactions that affect the average expression level of a reporter gene as well as its cell-to-cell variability (noise). We ectopically inserted an insulated MET3 promoter (MET3pr) flanked by ~1kb invariable sequences into thousands of genomic loci, allowing it to make contacts with different parts of the genome, and assayed the MET3pr activity in single cells. Changes of MET3pr activity in this case necessarily involve mechanisms that function over a distance. MET3pr has similar activities at most locations. However, at some locations, they deviate from the norm and exhibit three distinct patterns including low expression / high noise, low expression / low noise, and high expression / low noise. We provided evidence that these three patterns of MET3pr expression are caused by Sir2-mediated silencing, transcriptional interference, and 3D clustering. The clustering also occurs in the native genome and enhances the transcription of endogenous Met4-targeted genes. Overall, our results demonstrate that a small fraction of long-distance chromosomal interactions can affect gene expression in yeast.