Extensive transcript diversity and novel upstream open reading frame regulation in yeast

Area of Science:

• Molecular Biology
• Genomics
• Gene Expression Regulation

Background:

• The diversity of RNA transcripts in yeast (Saccharomyces cerevisiae) is not fully understood.
• Investigating transcriptional landscapes under different conditions can reveal novel regulatory mechanisms.

Purpose of the Study:

• To analyze the diversity of yeast transcripts under 18 different environmental conditions.
• To identify how variations in transcript ends (5' and 3') affect gene expression.
• To explore the role of upstream open reading frames (uORFs) and RNA-binding proteins in transcript heterogeneity.

Main Methods:

• RNA-sequencing was performed on yeast cells grown under 18 distinct environmental conditions.
• Analysis of 670,446,084 uniquely mapped reads and 377,263 poly-adenylated end tags.
• Comparative analysis of transcript 5' and 3' ends, identification of uORFs, and mutational analysis of selected genes.

Main Results:

• A large proportion of yeast genes are expressed under various conditions, with significant differences in transcript ends observed across environments.
• Differential transcription start and stop site usage was noted, particularly in stationary phase, grape juice, and salt-stimulated conditions.
• 431 upstream open reading frames (uORFs) were identified in alternate 5' ends, enriched during salt response, with some demonstrating regulatory roles in reporter assays.
• RNA-binding protein motifs were statistically enriched in alternate transcript ends.

Conclusions:

• Transcript end diversity is extensive in yeast and is regulated by environmental conditions.
• This heterogeneity in transcript ends has significant implications for gene expression regulation.
• The study provides a valuable resource for understanding yeast gene expression and RNA biology.