Translation efficiency changes at heat shock in Saccharomyces cerevisiae

Abstract

Both eukaryotic and prokaryotic cells respond to heat shock by engaging multiple regulatory mechanisms that preserve proteostasis, including adjustments in transcription, translation, and mRNA metabolism. Although the transcriptional response to heat stress in Saccharomyces cerevisiae has been well characterized, the extent to which translation efficiency (TE) is remodeled and how this remodeling contributes to protein synthesis remains less understood. Here, analysis of previously published ribosome profiling and RNA-seq data revealed that in S. cerevisiae, the TE varies during heat shock, depending on both temperature and stress duration. In contrast, TE remained largely stable in Escherichia coli under comparable conditions or during activation of {sigma}32, the main regulator of heat shock response in bacteria. In yeast, TE modulation patterns correlated with changes in protein abundance and differed markedly between early and late stages of stress. At 10 min, transcripts with short 5'UTRs and high codon optimality tended to display higher TE, primarily due to the easier ribosome engagement in these transcripts. By 30 min, the TE pattern across transcripts had changed drastically, suggesting increased availability of newly synthesized stress-response transcripts. These findings support a model in which early TE adjustments depend on intrinsic mRNA properties, whereas shifts in mRNA accessibility and transcriptional output shape later changes. The results highlight TE remodeling as a dynamic component of the heat-shock response in yeast and distinguish this behavior from the more buffered response observed in bacteria.