Structural information for explaining the molecular mechanism of protein biosynthesis

Protein biosynthesis is controlled by a number of proteins external to the ribosome, Of these, extensive structural investigations have been performed on elongation factor-Tu and elongation factor-G, This now gives a rather c omplete structural picture of the functional cycle of elongation factor-Tu and especially of the elongation phase of protein biosynthesis. The discove ry that three domains of elongation factor-G are structurally mimicking the amino-acylated tRNA in the ternary complex of elongation factor-Tu has bee n the basis of much discussion of the functional similarities and functiona l differences of elongation factor-Tn and elongation factor-G in their inte ractions with the ribosome, Elongation factor-G:GDP is nom thought to leave the ribosome in a state ready for checking the codon-anticodon interaction of the aminoacyl-tRNA contained in the ternary complex of elongation facto r-Tn. Elongation factor-G does this by mimicking the shape of the ternary c omplex. Other translation factors such as the initiation factor-2 and the r elease factor 1 or 2 are also thought to mimic tRNA. These observations rai se questions concerning the possible evolution of G-proteins involved in pr otein biosynthesis, (C) 1999 Federation of European Biochemical Societies.