Evolution at two levels of gene expression in yeast

Area of Science:

• Evolutionary Biology
• Molecular Biology
• Genetics

Background:

• Gene expression evolution studies primarily focus on mRNA levels, neglecting translational regulation.
• Understanding the evolution of translational control is crucial for a complete picture of gene regulation.

Purpose of the Study:

• To investigate the evolutionary divergence of translational regulation using ribosome profiling in Saccharomyces yeast.
• To compare the contributions of mRNA abundance changes and translation rate changes to regulatory evolution.

Main Methods:

• Ribosome profiling was employed on two Saccharomyces yeast species and their hybrid.
• This technique allowed simultaneous measurement of global mRNA levels and translation rates.

Main Results:

• Significant cis- and trans-acting regulatory divergence in translation was observed, affecting at least 35% of genes.
• Most translational divergence buffers changes in mRNA abundance, indicating stabilizing selection.
• Evidence for lineage-specific selection and conserved stop-codon readthrough was found.

Conclusions:

• Translational regulation is a major, underappreciated component of post-transcriptional regulatory divergence.
• Selection acts at multiple regulatory levels, challenging a simple coding vs. regulatory dichotomy.
• Future studies should consider both mRNA and translation levels to fully understand genotype-phenotype evolution.