Codon-anticodon interaction at the ribosomal E site

• Published in: The Journal of biological chemistry Vol. 261; no. 20; pp. 9140 - 9143
• Main Authors: Rheinberger, H J, Sternbach, H, Nierhaus, K H
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 15.07.1986; American Society for Biochemistry and Molecular Biology
• Subjects: Acylation; Anticodon - metabolism; Binding Sites; Binding, Competitive; Biological and medical sciences; Codon - metabolism; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Molecular and cellular biology; Molecular genetics; Peptide Elongation Factor G; Peptide Elongation Factors - metabolism; Poly A - pharmacology; Poly U - pharmacology; Ribosomes - metabolism; RNA, Bacterial - metabolism; RNA, Messenger - metabolism; RNA, Transfer - metabolism; RNA, Transfer, Amino Acyl - metabolism; Translation. Translation factors. Protein processing; Ribosome; Escherichia coli; T RNA; Bacteria; Binding site; Escherichieae; Enterobacteriaceae
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)67629-X

The question of whether or not the tRNA at the third ribosomal binding site specific for deacylated tRNA (E site) undergoes codon-anticodon interaction was analyzed as follows. Poly(U)-programmed ribosomes each carrying two [14C]tRNAPhe molecules were subjected to a chasing experiment using various tRNA species. At 0 degree C Ac[3H]Phe-tRNAPhe did not trigger any chasing whereas deacylated cognate tRNAPhe provoked a strong effect; non-cognate tRNALys was totally ineffective. This indicates that the second [14C]tRNAPhe cannot be present at the A site but rather at the E site (confirming previous observations). In the presence of poly(U) or poly(A) ribosomes bound the cognate tRNA practically exclusively as second deacylated tRNA, i.e. [14C]tRNAPhe and [14C]tRNALys, respectively. Thus, the second deacylated tRNA binds in a codon-dependent manner. [14C]tRNALys at the P site and Ac[3H]Lys-tRNALys at the A site of poly(A)-primed ribosomes were translocated to the E and P sites, respectively, by means of elongation factor G. The E site-bound [14C]tRNALys could be significantly chased by cognate tRNALys but not by non-cognate tRNAPhe, indicating the coded nature of the E site binding. Additional evidence is presented that the ribosome accommodates two adjacent codon-anticodon interactions at either A and P or P and E sites.