The amino acid substitution affects cellular response to mistranslation

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Mistranslation, the misincorporation of amino acids not specified by the standard genetic code, is a natural biological process occurring in all organisms.
• While cells possess mechanisms to manage increased mistranslation, high levels can induce proteotoxic stress, potentially contributing to disease.
• Human genomes harbor tRNA variants with the capacity to induce mistranslation.

Purpose of the Study:

• To compare the effects of two distinct tRNA variants, which cause mistranslation at similar frequencies but different amino acid substitutions, on cellular growth, transcriptome, and genetic interactions in Saccharomyces cerevisiae.
• To investigate how specific amino acid substitutions resulting from mistranslation influence cellular responses and potentially disease pathogenesis.

Main Methods:

• Utilized engineered tRNA variants in Saccharomyces cerevisiae to induce specific amino acid substitutions (alanine for proline, serine for arginine) at defined frequencies.
• Assessed cellular growth rates and heat shock responses under conditions of induced mistranslation.
• Performed transcriptome analysis to identify gene expression changes in response to different mistranslation events.
• Analyzed negative synthetic genetic interactions to understand the cellular impact of distinct mistranslation types.

Main Results:

• Both tRNA variants reduced growth rate, with the serine-for-arginine substitution having a more pronounced effect than alanine-for-proline.
• The serine-for-arginine tRNA induced a significant heat shock response, while the alanine-for-proline tRNA elicited a minimal response.
• Transcriptome analysis revealed unique sets of up- and down-regulated genes specific to each type of mistranslation.
• The number and extent of negative synthetic genetic interactions varied depending on the specific amino acid substitution caused by mistranslation.

Conclusions:

• The impact of mistranslation on proteotoxic stress and disease exacerbation is dependent on the specific tRNA variant and the resulting amino acid substitution.
• Distinct mistranslating tRNAs, characterized by unique transcriptomes and genetic interaction profiles, have the potential to differentially influence the pathogenesis of various diseases.