The Roles of Compensatory Evolution and Constraint in Aminoacyl tRNA Synthetase Evolution

摘要: Mitochondrial protein translation requires interactions between transfer RNAs encoded by the mitochondrial genome (mt-tRNAs) and aminoacyl tRNA synthetase proteins (mt-aaRS) nuclear genome. It has been argued that animal mt-tRNAs have higher deleterious substitution rates relative to their nuclear-encoded counterparts, cytoplasmic tRNAs (cyt-tRNAs). This dynamic predicts elevated of compensatory evolution mt-aaRS interact with mt-tRNAs, aaRS cyt-tRNAs (cyt-aaRS). We find do evolve at significantly (exemplified dN dN/dS) cyt-aaRS, across mammals, birds, Drosophila. While this pattern supports a model evolution, level which gene is expressed more general predictor evolutionary rate. expression explains 10-56% variance in dN/dS, cyt-aaRS are highly addition having lower dN/dS values mt-aaRS, consistent genes being evolutionarily constrained. Furthermore, we no evidence positive selection acting on either class protein, as would be expected under evolution. Nevertheless, signature faster persists mammalian, but not bird or Drosophila, lineages after controlling for expression, suggesting some additional effect mammalian mt-aaRS. conclude strongest factor governing differential amino acid interacting versus factors, important differences molecular among taxonomic groups.