PROTEIN-RNA RECOGNITION

Specific interactions between RNAs and proteins are fundamental to many cellular processes, including the assembly and function of ribonucleoprotein particles (RNPs), such as ribosomes and spliceosomes and the post-transcriptional regulation of gene expression. Among the complexes studied to date are small RNAs bound to individual amino acids, tRNAs and tRNA fragments bound to their cognate aminoacyl-tRNA synthetases, and a variety of proteins bound to RNA single strands, hairpins, irregular helices, and tertiary structures stabilized by bound cations. Several proteins use a beta-sheet surface to bind RNAs, and others insert an alpha-helix into the widened major groove of a noncanonical RNA helix. Distortion or rearrangement of the RNA structure by bound protein is a common theme. The structural details of protein-RNA complexes are being resolved by nuclear magnetic resonance (NMR) and X-ray crystallography, but thorough thermodynamic analyses of recognition mechanisms have yet to be performed.