Nc. Kyrpides et Cr. Woese, UNIVERSALLY CONSERVED TRANSLATION INITIATION-FACTORS, Proceedings of the National Academy of Sciences of the United Statesof America, 95(1), 1998, pp. 224-228
The process by which translation is initiated has long been considered
similar in Bacteria and Eukarya but accomplished by a different unrel
ated set of factors in the two cases. This not only implies separate e
volutionary histories for the two but also implies that at the univers
al ancestor stage, a translation initiation mechanism either did not e
xist or was of a different nature than the extant processes, We demons
trate herein that (i) the ''analogous'' translation initiation factors
IF-1 and eIF-1A are actually related in sequence, (ii) the ''eukaryot
ic'' translation factor SUI1 is universal in distribution, and (iii) t
he eukaryotic/archaeal translation factor eIF-5A is homologous to the
bacterial translation factor EF-P. Thus, the rudiments of translation
initiation would seem to have been present in the universal ancestor s
tage. However, significant development and refinement subsequently occ
urred independently on both the bacterial lineage and on the archaeal/
eukaryotic line.