EFFECT OF PHOTOCROSSLINKING ON ESCHERICHIA COLI tRNA STRUCTURE

Abstract— The effect of photocrosslinking s ⁴ U ₈ with C ₁₃ on the structure of E. coli tRNA has been examined by high resolution NMR. Photocrosslinking affects both the structure and the enzymatic acylation of tRNA. The NMR measurements demonstrate that except for the s ⁴ U ₈.A₁₄ base pair, there is no evidence that photocrosslinking perturbs any of the common tertiary structure interactions. However, this modification does perturb several resonances which are assigned to the secondary structure base pairs of the hU stem and the terminal base pair of the acceptor stem. The variable effect of photocrosslinking on the extent and rate of enzymatic acylation of different tRNA is attributed to different recognition sites for tRNA by the cognate synthetases.