Editing Reactions from the Perspective of RNA Structure.

Abstract RNA editing belongs to the large group of processing reactions that are required to convert primary RNA transcripts into mature and functional transcripts. The main determinants of specificity rest in the three-dimensional structures of RNA and protein molecules that act in concert to coordinate and regulate the posttranscriptional steps in gene expression. Many high-resolution structures of RNA-protein complexes, including the ribosome, have become available during the last decade and have offered detailed views of the intracellular RNA world. The focus of this review is to highlight the contributions of RNA structure to the specificity and efficiency of RNA editing. Editing occurs by a variety of mechanisms, but the fidelity of the reactions critically depends on the specific sequences and structures of the RNA molecules involved and on their recognition by trans-acting factors, including proteins and RNA. Hence, the editing machineries, also termed "editosomes", make use of RNA-RNA, RNA-protein and protein-protein interactions to achieve specificity and efficiency. High-resolution structures of protein components of various editosomes exist, but reports of RNA structures and RNA-protein complexes are still limited. Progress can be expected in the near future from more efficient purification and crystallization techniques developed in other fields of RNA processing, like RNA interference, splicing and catalysis. Although each structure reveals only a static view of a multistep reaction, they will eventually lead to a better understanding of the dynamic molecular machines involved in RNA editing. [ABSTRACT FROM AUTHOR]