RNA Structure

Abstract Ribonucleic acid (RNA) molecules perform their function in living cells by adopting specific and highly complex 3‐dimensional structures. Like proteins, RNA structure can be described in terms of its primary (sequence), secondary (hairpins, bulges and internal loops), tertiary (A‐minor motif, 3‐way junction, pseudoknot, etc.) and quaternary structure (supermolecular organisation). Watson–Crick base pairs as well as other noncanonical base interactions are the basic building blocks of RNA secondary and tertiary structures. Metal ions are essential for the stabilisation of RNA tertiary structures and for catalytic function. In the past decade, there has been a tremendous advance in RNA structure determination, with the successful determination of the ribosome structures, as well as many other folded large RNAs. These studies have given us a unique new opportunity to understand the structure–function relationship of RNA molecules to an unprecedented level of insight. Key Concepts: Double helical tracts separated by single‐stranded nucleotides represent the basic building block of RNA structure. Hairpins (or stem–loops) are the most common element of RNA secondary structure. RNA secondary structure can generally be predicted successfully from sequence analysis and thermodynamic calculation. RNA secondary structure is generally more stable than its tertiary structure. RNA three‐dimensional structures form by joining together the different secondary structure elements through the formation of long‐range tertiary interactions. Coaxial stacking between double‐stranded helices at junctions where helices come together is a major determinant of higher order RNA tertiary structure. Multivalent ions are often important for thermodynamic stabilisation and catalytic activities of RNA tertiary structures.