All the crucial proteins in our bodies must fold into complex shapes to do their jobs. These snarled molecules grip other molecules to move them around, to speed up important chemical reactions or to grab onto our genes, turning them “on” and “off” to affect which proteins our cells make. Recently, scientists have discovered that RNA-the stringy molecule that translates our genetic code into protein-can act a lot like a protein itself. RNA can form loopy bundles that shut genes down or start them up without the help of proteins. Since the discovery of these RNA clumps, called “riboswitches,” in 2002, scientists have been striving to understand how they work and how they form. Now, researchers at Stanford University are looking closer than ever at how the three-dimensional twists and turns in a riboswitch come together by grabbing it and tugging it straight. By physically pulling on this loopy RNA, they have determined for the first time how a three-dimensional molecular structure folds, step by step.
