Stop Codon Usage as a Window into Genome Evolution: Mutation, Selection, Biased Gene Conversion and the TAG Paradox.

ABSTRACT: Protein coding genes terminate with one of three stop codons (TAA, TGA, or TAG) that, like synonymous codons, are not employed equally. With TGA and TAG having identical nucleotide content, analysis of their differential usage provides an unusual window into the forces operating on what are ostensibly functionally identical residues. Across genomes and between isochores within the human genome, TGA usage increases with G + C content but, with a common G + C → A + T mutation bias, this cannot be explained by mutation bias-drift equilibrium. Increased usage of TGA in G + C-rich genomes or genomic regions is also unlikely to reflect selection for the optimal stop codon, as TAA appears to be universally optimal, probably because it has the lowest read-through rate. Despite TAA being favored by

SUBMITTER: Ho AT 

PROVIDER: S-EPMC9348620 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature