Biopolymers and cell. 1989. Volume 5. № 2. 62 - 69

S. A. Nekhay, E. M. Saminsky

BINDING OF YEAST tRNAphe WITH ANTICODON ARM TO ESCHER1CHIA COL! SOS SUBUNITS AND 70S RIBOSOMES

Summary

    The 15-nucleotide analog of the yeast tRNAPhe anticodon arm binds reversibly two sites of E. coli poly (U)-programmed 305 ribosomal subunits. There is a competition between the tRNAphe fragment and tRNAPhe for this binding. It is blocked totally by edeine and partially by tetracycline. The site with higher affinity for fragment has been characterized by association and dissociation rate constants and by equilibrium affinity constant. The second site reveals the affinity constant at 20 °C one order of magnitude lower. 70S ribosomes bind the fragment quantitatively and qualitatively in almost the same way as SOS subunits. The association of the fragment with 80S subunits is quite similar to analogous association of Phe-tRNAphe (Kirillov S. V. et al., 1980, Nucl. Acids Res., 8, 186-193). It permits supposing by analogy with the latter that the site with high affinity for the fragment can be presumably identified as a part of the P-site, and the site with lower affinity — as a part of the A-site of ribosomc.