Analysis of Stop Codons within Prokaryotic Protein-Coding Genes Suggests Frequent Readthrough Events.

ABSTRACT: Nonsense mutations turn a coding (sense) codon into an in-frame stop codon that is assumed to result in a truncated protein product. Thus, nonsense substitutions are the hallmark of pseudogenes and are used to identify them. Here we show that in-frame stop codons within bacterial protein-coding genes are widespread. Their evolutionary conservation suggests that many of them are not pseudogenes, since they maintain dN/dS values (ratios of substitution rates at non-synonymous and synonymous sites) significantly lower than 1 (this is a signature of purifying selection in protein-coding regions). We also found that double substitutions in codons-where an intermediate step is a nonsense substitution-show a higher rate of evolution compared to null models, indicating that a stop codon was introd

SUBMITTER: Belinky F 

PROVIDER: S-EPMC7918605 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature