SUS1 introns are required for efficient mRNA nuclear export in yeast

Area of Science:

• Molecular Biology
• Gene Expression Regulation
• Yeast Genetics

Background:

• Sus1/ENY2 is crucial for mRNA synthesis and export, linking transcription and mRNA export.
• Most yeast genes lack introns, but SUS1 contains two, a feature conserved across species.
• The function of SUS1 is linked to its intronic sequences and splicing efficiency.

Purpose of the Study:

• To investigate the evolutionary conservation and functional significance of SUS1 introns.
• To explore the regulation of SUS1 expression, including splicing, nonsense-mediated decay (NMD), and the role of splicing factors.
• To understand the interplay between splicing, translation, and decay in mRNA biogenesis.

Main Methods:

• Analysis of SUS1 intron conservation and function.
• Creation and testing of intronic mutations affecting SUS1 splicing.
• Assessment of intron-less SUS1 rescue capabilities.
• Investigation of SUS1 RNA and protein levels.
• Evaluation of the roles of the NMD pathway and Mud2.

Main Results:

• SUS1 intron presence is evolutionarily conserved and critical for Sus1 function.
• SUS1 splicing is inefficient but responsive to cellular conditions; mutations impact mRNA export and growth.
• An intron-less SUS1 partially rescues sus1Δ phenotypes, indicating intron importance.
• Splicing of SUS1 introns is interdependent and influenced by exonic sequences.
• Nonsense-mediated decay (NMD) and Mud2 influence SUS1 expression.

Conclusions:

• Splicing, translation, and decay are involved in regulating early mRNA biogenesis events.
• A balance of splicing isoforms from a single gene, like SUS1, is essential.
• The study highlights the complex regulation of gene expression through splicing and decay pathways.