title: The evolution and functional repertoire of translation proteins following the origin of life.
abstract: BACKGROUND
  The RNA world hypothesis posits that the earliest genetic system consisted of informational RNA molecules that directed the synthesis of modestly functional RNA molecules. Further evidence suggests that it was within this RNA-based genetic system that life developed the ability to synthesize proteins by translating genetic code. Here we investigate the early development of the translation system through an evolutionary survey of protein architectures associated with modern translation.
  
  
  RESULTS
  Our analysis reveals a structural expansion of translation proteins immediately following the RNA world and well before the establishment of the DNA genome. Subsequent functional annotation shows that representatives of the ten most ancestral protein architectures are responsible for all of the core protein functions found in modern translation.
  
  
  CONCLUSIONS
  We propose that this early robust translation system evolved by virtue of a positive feedback cycle in which the system was able to create increasingly complex proteins to further enhance its own function.
authors.affiliation: Department of Microbiology, University of Washington, Box 357242, Seattle, WA 98195, USA. adg1000@u.washington.edu
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Goldman
authors.forename: Ram
authors.initials: R
authors.lastname: Samudrala
authors.forename: John A
authors.initials: JA
authors.lastname: Baross
mesh_terms: D019143:Evolution, Molecular; D014176:Protein Biosynthesis / Q000502:physiology*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D011506:Proteins