Why Is the UAG (Amber) Stop Codon Almost Absent in Highly Expressed Bacterial Genes?

ABSTRACT: The genome hypothesis postulates that genes in a genome tend to conform to their species' usage of the codon catalog and the GC content of the DNA. Thus, codon frequencies differ across organisms, including the three termination codons in the standard genetic code. Here, we analyze the frequencies of stop codons in a group of highly expressed genes from 196 prokaryotes under strong translational selection. The occurrence of the three translation termination codons is highly biased, with UAA (ochre) being the most prevalent in almost all bacteria. In contrast, UAG (amber) is the least frequent termination codon, e.g., only 321 occurrences (7.4%) in E. coli K-12 substr. W3110. Of the 253 highly expressed genes, only two end with an UAG codon. The strength of the selective bias against UAG in

SUBMITTER: Belin D 

PROVIDER: S-EPMC8954436 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature