LaDonne H. Schulman

Recognition of tRNAs by aminoacyl-tRNA synthetases.

Publisher Summary This chapter describes the recognition of tRNAs by aminoacyl-tRNA synthetases. The highly specific selection of tRNA substrates by aminoacyl-tRNA synthetases is an intriguing problem in RNA-protein recognition. Synthetases specific for each of the 20 amino acids encounter a pool of tRNAs in the cell having similar overall structures. The selection of the appropriate tRNAs for the attachment of each amino acid occurs by the formation of RNA-protein contacts unique to each cognate tRNA-synthetase pair. The sites in tRNAs that govern these interactions have been investigated by a variety of techniques discussed in the chapter, such as the assays of the amino-acid-acceptor specificity of tRNA. The role of the anticodon in recognition, role of the acceptor Stem and discriminator base, and role of modified bases is discussed in the chapter. The anticodon is not required for the recognition of tRNA AIa , and possibly tRNA Ser ; these and all other E. coli tRNAs probably contain identity elements in the anticodon that are crucial for the discrimination of cognate and noncognate tRNAs by synthetases in vivo. In addition, a number of E. coli tRNAs contain important recognition elements for their cognate synthetases in the acceptor stem and/or at the discriminator site.

Recognition of altered E.coli formylmethionine transfer RNA by bacterial T factor

Abstract Treatment of E. coli formylmethionine tRNA with sodium bisulfite produces six C → U base changes in the tRNA structure. Four of these modifications have no effect on the ability of tRNAfMet to be aminoacylated or formylated. Prior to bisulfite treatment, Met-tRNAfMet is not able to form a ternary complex with bacterial T factor and GTP, as measured by Sephadex G-50 gel filtration. After bisulfite treatment, a large portion of the modified tRNA is bound as T-GTP-Met-tRNAfMet. Formylation of bisulfite-modified Met-tRNAfMet completely eliminates T factor binding. Unmodified tRNAfMet is unique among the tRNAs sequenced to date in having a non-hydrogen-bonded base at the 5′ terminus. Bisulfite-catalyzed conversion of this unpaired C1 to U1 results in formation of a normal U1-A73 base pair at the end of the acceptor stem. It is likely that this structural alteration is responsible for the recognition of bisulfite-modified Met-tRNAfMet by T factor.

Five Specific Protein-Transfer RNA Interaction

(1980). Five Specific Protein-Transfer RNA Interaction. Critical Reviews in Biochemistry: Vol. 9, No. 3, pp. 207-251.

Studies of the Rous Sarcoma virus RNA: Characterization of the 5′-terminus

Abstract The 5′ terminus of the Rous Sarcoma Viral 30-40S RNA was characterized as follows: Unlabeled RNA was treated with polynucleotide kinase and (γ-32P) ATP. Degradation of the 5′-(32P) RNA with alkali yielded labeled pAp while degradation with venom phosphodiesterase yielded labeled 5′-AMP. Dephosphorylation with alkaline phosphatase was unnecessary for the RNA to accept32P indicating the presence of 5′-OH ends. This establishes that the base at the 5′ end of Rous Sarcoma Viral 30-40S RNA is adenine.