Emerging structural themes in large RNA molecules
Extensive networks of tertiary interactions give rise to unique, highly organized domain architectures that characterize the three-dimensional structure of large RNA molecules. Formed by stacked layers of a near-planar arrangement of contiguous coaxial helices, large RNA molecules are relatively flat in overall shape. The functional core of these molecules is stabilized by a diverse set of tertiary interaction motifs that often bring together distant regions of conserved nucleotides. Although homologous RNAs from different organisms can be structurally diverse, they adopt a structurally conserved functional core that includes preassembled active and/or substrate binding sites. These findings broaden our understanding of RNA folding and tertiary structure stabilization, illustrating how large, complex RNAs assemble into unique structures to perform recognition and catalysis. âº Analysis of recent structures of large RNA molecules shows that they have organized domain architectures. âº The structures are stabilized by a wide range of tertiary interaction motifs. âº In many instances, homologous RNAs have a common structural core that is stabilized by different peripheral elements. âº Active sites and/or substrate binding sites are preassembled. âº Recognition involves both shape complementarity and specific molecular contacts.