The Importance of Being Modified: Roles of Modified Nucleosides and Mg2+ in RNA Structure and Function

Abstract

Publisher Summary This chapter summarizes the relationships between modified nucleosides and transfer RNA (tRNA) function. In vivo and in vitro syntheses of modified nucleoside-containing RNAs have been developed for physicochemical and biochemical studies. The different approaches to RNA synthesis are compared in the chapter. An understanding of the chemistry, structure, and function of modified nucleosides of tRNAs is applicable to the study of modified nucleosides of other RNAs and DNA. The structure–function relationships of the simplest of nucleoside modifications may provide insights into the “RNA World” and could be applied to the design of nucleic acids with new or altered functions. Nucleosides are modified after the polymerization of the nucleic acid. To accomplish site-specific modifications of the bases in DNA and the bases and ribose of RNA, a very large investment in genetic information, energy, and material resources has been made d. Nucleic-acid modifications have been linked to the control of gene expression at both the level of transcription and translation. Although a few modifications have been found in DNA, 93 modified nucleosides exist in various RNAs. Nucleic-acid stability is enhanced through the modifications that introduce local positive charges, neutralizing the anionic phosphate backbone.