Stop codons in bacteria are not selectively equivalent.

ABSTRACT:

Background

The evolution and genomic stop codon frequencies have not been rigorously studied with the exception of coding of non-canonical amino acids. Here we study the rate of evolution and frequency distribution of stop codons in bacterial genomes.

Results

We show that in bacteria stop codons evolve slower than synonymous sites, suggesting the action of weak negative selection. However, the frequency of stop codons relative to genomic nucleotide content indicated that this selection regime is not straightforward. The frequency of TAA and TGA stop codons is GC-content dependent, with TAA decreasing and TGA increasing with GC-content, while TAG frequency is independent of GC-content. Applying a formal, analytical model to these data we found that the relationship between st

SUBMITTER: Povolotskaya IS 

PROVIDER: S-EPMC3549826 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature