Dataset Information

ENVIRONMENT MODULATES PROTEIN HETEROGENEITY THROUGH TRANSCRIPTIONAL AND TRANSLATIONAL STOP CODON RECODING

ABSTRACT: In order to systematically assess the frequency and origin of stop codon recoding events, we designed a library of reporters. We introduced premature stop codons into mScarlet that enabled high-throughput quantification of protein synthesis termination errors in E. coli using fluorescent microscopy. We found that under stress conditions, stop codon recoding may occur with a rate as high as 80%, depending on the nucleotide context, suggesting that evolution frequently samples stop codon recoding events. The analysis of selected reporters by mass spectrometry and RNA-seq showed that not only translation but also transcription errors contribute to stop codon recoding. The RNA polymerase is more likely to misincorporate a nucleotide at premature stop codons. Proteome-wide detection of stop codon recoding by mass spectrometry revealed that temperature regulates the expression of cryptic sequences generated by stop codon recoding in E. coli. Overall, our findings suggest that the environment influences the accuracy of protein production which increases protein heterogeneity when the organisms need to adapt to new conditions.

ORGANISM(S): Escherichia coli str. K-12 substr. MG1655

PROVIDER: GSE226936 | GEO | 2024/03/28

REPOSITORIES: GEO

ACCESS DATA

Similar Datasets

Project description:Terminating protein translation accurately and efficiently is critical for both protein fidelity and ribosome recycling for continued translation. The three bacterial release factors (RFs) play key roles: RF1 and 2 recognize stop codons and terminate translation; and RF3 promotes disassociation of bound release factors. Probing release factors mutations with reporter constructs containing programmed frameshifting sequences or premature stop codons had revealed a propensity for readthrough or frameshifting at these specific sites, but their effects on translation genome-wide have not been examined. We performed ribosome profiling on a set of isogenic strains with well-characterized release factor mutations to determine how they alter translation globally. Consistent with their known defects, strains with increasingly severe release factor defects exhibit increasingly severe accumulation of ribosomes over stop codons, indicative of an increased duration of the termination/release phase of translation. Release factor mutant strains also exhibit increased occupancy in the region following the stop codon at a significant number of genes. Our global analysis revealed that, as expected, translation termination is generally efficient and accurate, but that at a significant number of genes (≥ 50) the ribosome signature after the stop codon is suggestive of translation past the stop codon. Even native E. coli K-12 exhibits the ribosome signature suggestive of protein extension, especially at UGA codons, which rely exclusively on the reduced function RF2 allele of the K-12 strain for termination. Deletion of RF3 increases the severity of the defect. We unambiguously demonstrate readthrough and frameshifting protein extensions and their further accumulation in mutant strains for a few select cases. In addition to enhancing recoding, ribosome accumulation over stop codons disrupts attenuation control of biosynthetic operons, and may alter expression of some overlapping genes. Together, these functional alterations may either augment the protein repertoire or produce deleterious proteins.

Dataset Information

ENVIRONMENT MODULATES PROTEIN HETEROGENEITY THROUGH TRANSCRIPTIONAL AND TRANSLATIONAL STOP CODON RECODING

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure