RNA Structure: Tetraloops

Abstract

Ribonucleic acid (RNA) hairpins are among the most common RNA secondary structural elements that are frequently capped by tetraloops. An RNA tetraloop structure is composed of a WatsonCrick base-paired stem and four loop nucleotides. The structure is compact and stable. The first and the fourth nucleotides form a base pair in most of the tetraloops, leaving two unpaired nucleotides in the loop. A sharp turn in the backbone is stabilized by ribosebase, basephosphate hydrogen bonds and base stacking interactions. Tetraloops help in the folding of RNA by initiating the process. Additionally, they provide sites for RNA tertiary contacts and for protein binding, facilitating the assembly of ribonucleoprotein particles. Certain interactions, some of which are sequence-specific and others structure-specific, can be involved in the recognition of tetraloops by proteins and RNAs. Key concepts:Key concepts: RNA hairpins play important structural and functional roles in RNA. Tetraloops help the folding of RNA and provide sites for RNARNA and RNAprotein interactions. U turn motif, a sharp backbone turn in tetraloops, is stabilized by ribosebase, basephosphate hydrogen bonds and base stacking interactions.