Modification and editing of RNA: historical overview and important facts to remember

Abstract

Abstract RNA plays a central role in many cellular processes and several peculiarities of RNAs are probably relics of an ancient primordial RNA World. To fulfill their multiple present-day functions, these molecules need more than just four canonical bases. The numerous modified nucleosides that are formed during processing of nascent precursor RNA transcripts clearly serve this purpose. The recent discoveries of RNA-guided RNA modification machineries and of RNA editing processes leading to selected conversions of one base into another in the pre-RNA, add new dimensions to the problems surrounding the biosynthesis and functions of modified and edited nucleosides in RNA. The majority of these so-called minor or edited nucleosides appear to improve the performance of the matured RNA by working more efficiently and accurately in various steps of cellular metabolism. However, their effects can be subtle and not easy to demonstrate either in vivo or in vitro. Here, we review some basic characteristics of the modified nucleosides and of enzymes leading to such post-transcriptional modifications and editing of RNA