The Versatile Transfer RNA Molecule: Crystallography of Yeast tRNAAsp

The molecular structure of yeast tRNAAsp, a short extra-loop tRNA, was solved at 3 A resolution in two closely related crystal forms. The resulting model confirms the folding originally found in tRNAPhe: major differences concern the conformations of the loops and the relative positioning of the acceptor and anticodon stems which are more open, conferring to the tRNAAsp molecule its boomerang like shape. Crystal packing involves self-complementary GUC anticodon interactions thus making the structure a tempting model of a tRNA interacting with mRNA on the ribosome. The chemical stability of the tRNA in the crystalline state and in solution is compared using end-labelling and rapid sequencing gel methodologies. Partial splitting of the ribose-phosphate backbone in the anticodon loop was observed in solution but not in the crystal where the splitting is more pronounced in the D-loop.