Codon usage and base composition in Archaea

APTEKMANN AA; NADRA AD

Bernal

Congreso; II RABAnc 2018; 2018

Universidad de Quilmes

Base composition is a relatively simple characteristic to evaluate. It is characteristic of anorganism ́s genomes or, in general, of any fragment of DNA or RNA, and represents the amount ofeach base in a strand of the nucleic acid molecule. GC content variation between genomes is acentral issue in evolutionary genomics, where one of ther most widely accepted theories is thethermal adaptation hypothesis which proposes that thermophiles tend to have a higher G + Ccontent. In this work we analyzed base composition and codon usage in all available archaealgenomes.By analyzing Shannon ́s entropy, we show that there is no evident bias in codon usage related tooptimal growth temperature in our dataset. On the other hand, we show that thermal adaptationhypothesis is not sustained by our dataset. Furthermore, we show that this dependency only holdsfor RNA with a function dependent upon their structure.These findings have a significant consequence on the traditional way to establish evolutionaryrelations, which are commonly based on 16s RNA. Since 16s RNA are biased in their basecomposition, evolutionary distances between organisms living at similar temperatures might beunderestimated.