The Hasp Motif: A New Type of RNA Tertiary Interactions

RNA structural motifs are recurrent structural elements occurring in RNA molecules. They play essential roles in consolidating RNA tertiary structures and in binding proteins. Recently, we discovered a new type of RNA structural motif, namely the hasp motif, from 27 RNA molecules. The hasp motif comprises three nucleotides which form a structure similar to a hasp. Two consecutive nucleotides in the motif come from a double helix and the third one comes from a remote stand. The hasp motif makes two helices approach each other, which leads to RNA structure folding. All the identified hasp motifs reveal a consensus structural pattern although their sequences are not conserved. Hasp motifs are observed to reside both inside and on the surface of RNA molecules. Those inside RNA molecules help consolidate RNA tertiary structures while the others locating on the surface are evidenced to interact with proteins. The wide existence of hasp motifs indicates that hasp motifs are quite essential in both keeping RNA structures’ stableness and helping RNA perform their functions in biological processes.