The hydrolysis of several tRNAs by an endonuclease extracted from the venom of Nuju oxiuna and specific for double-stranded, or at least highly ordered, regions has been studied under various experimental conditions.It is shown that the hydrolysis patterns of yeast tRNAPhe, tRNAval and tRNAAFP in the isolated state are similar, most of the cuts occurring in the anticodon and acceptor stems. Ionic conditions are able to modify the hydrolysis pattern. The origin of these modifications is discussed.The protection against ribonuclease action, afforded to tRNAPh", tRNA""' and tRNA"'P by the cognate aminoacyl-tRNA synthetase, is analyzed. It is shown that in all cases the anticodon stem is protected. The 3'-terminal region does not seem to be tightly engaged in the complex with the aminoacyl-tRNA synthetase. These results are discussed in the light of information on contact areas previously obtained by ultraviolet cross-linking techniques.The effects of the small ligands (ATP and amino acid) on the protection afforded to the tRNA by the cognate synthetase, have been studied. In the valine and aspartic acid systems, ATP induced a modification of the tRNAenzyme complex leading to differences in the hydrolysis pattern of the 3'-accepting region.The effects of aminoacylation on the cleavage of tRNAPhe, tRNA""' and tRNAA'p were also studied. Whereas no modification of the cleavage map was observed in the aspartic system, aminoacylation resulted in slight but significant modifications of the hydrolysis pattern for tRNAPh" and tRNAva' in the 3'-terminal region.Aminoacylation is one of the first steps of protein biosynthesis. This reaction includes several components (tRNAs, aminoacyl-tRNA synthetases, ATP, amino acids) and consists in several steps, the mechanisms of which have been intensively studied [l]. One of the most interesting questions is to know whether the tRNA molecules undergo conformational changes in the course of the aminoacylation process. Indeed, recent results showed such structural modifications, upon binding to the cognate aminoacyl-tRNA synthetase, in the yeast phenylalanyl system [2,3]. These changes may be responsible for the appearance of the catalytic activity or even for the specificity of aminoacylation [3]. Furthermorc, it has been shown that small ligands of aminoacyl-tRNA synthetases were able to alter the relations between tRNAPhe and phenylalanyl-tRNA synthetase, leading to asymmetric behaviour of the enzyme [4].The conformation of the aminoacyl-tRNA itself has been extensively studied and very conflicting results were reportcd in the litcrature concerning structure differences between aminoacylated and non-acylated tRNAs. In the last few years, however, several papers reported structural modifications of tRNA upon aminoacylation [5 -101.Finally, it is quite conceivable that cations may trigger or contribute to conformational changes in the isolated or ~~ ~
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.