Translation Regulation: The Archaea-Eukaryal Connection

Translation, as an essential cellular process, is very well conserved through evolution. Nonetheless, the translational apparatus, namely the ribosomes and the accessory protein factors that assist all the steps of translation, have incurred a certain divergence in the three domains of cellular descent, the Bacteria, the Archaea and the Eukarya. The strongest evolutionary divergence is seen at the level of the initiation step, during which the ribosomes identify the start codon on the mRNA and set the correct reading frame for decoding. Initiation is a crucial event that sets the general rate of translation and is the target of most mechanisms of translational regulation. While the Bacteria have a very streamlined translational apparatus, especially as regards the translation initiation factors, the other prokaryotic domain, the Archaea, displays an unexpected degree of complexity. Moreover, the components of the archaeal translational apparatus are evolutionarily closer to those of the Eukarya, and the Archaea share with the Eukarya certain translation factors that are not found in Bacteria. This chapter reviews the similarities and the differences of the several steps of translation in the three domains of life, with special emphasis on the still poorly understood connection between Archaea and Eukarya.