Recognition of Cognate Transfer RNA by the 30S Ribosomal Subunit
Crystal structures of the 30S ribosomal subunit in complex with messenger RNA and cognate transfer RNA in the A site, both in the presence and absence of the antibiotic paromomycin, have been solved at between 3.1 and 3.3 angstroms resolution. Cognate transfer RNA (tRNA) binding induces global domain movements of the 30S subunit and changes in the conformation of the universally conserved and essential bases A1492, A1493, and G530 of 16S RNA. These bases interact intimately with the minor groove of the first two base pairs between the codon and anticodon, thus sensing Watson-Crick base-pairing geometry and discriminating against near-cognate tRNA. The third, or "wobble," position of the codon is free to accommodate certain noncanonical base pairs. By partially inducing these structural changes, paromomycin facilitates binding of near-cognate tRNAs.
© 2001 American Association for the Advancement of Science. 12 March 2001; accepted 3 April 2001. We thank S. Ginell and A. Joachimiak (APS) and M. MacDonald and E. Duke (Daresbury) for their help and advice with synchrotron data collection; P. Nissen for advice on making Fig. 3; and B. T. Wimberly and K. Nagai for comments on the manuscript. Supported by the Medical Research Council (U.K.) and grant GM 44973 from the NIH to S. W. White and V.R.. D.E.B. was the recipient of a Human Frontier Science Program postdoctoral fellowship.
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