A new study has uncovered the rules of RNA recoding--a genetic-editing method cells use to expand the number of proteins assembled from the DNA code. The shape a particular RNA molecule adopts determines how the molecule gets edited inside cells.

Credit: Nicolle Rager, National Science Foundation

DNA (left) encodes the instructions for making protein, but cells can't read them directly. Instead, the DNA code is copied first into RNA in a process called transcription. RNA includes coding regions that direct protein assembly (green) and non-coding regions--called introns--that play a regulatory role (yellow, pink). By studying the RNA code for the nervous- system protein, synaptotagmin, in several different insects, Reenan uncovered the general rules of RNA editing. Each insect's RNA folds differently and the structures determine how the molecules get edited inside cells.

This figure illustrates editing of fruit fly and butterfly RNA molecules. RNA folding brings regulatory regions (yellow, pink shapes) together with editing sites (green shapes). The resulting "knots" of fruit fly RNA (upper panel) and "loops" of butterfly RNA (lower panel) guides editing enzymes to sites destined for modification. RNA editing lets cells produce a variety of different proteins from a single DNA code (right). The altered proteins often have different functions from their unmodified counterparts.

Credit: Nicolle Rager, National Science Foundation