Scientists at the SLAC National Accelerator Laboratory in California have, for the first time, observed a chemical interacting with an RNA “switch” that's responsible for regulating the production of proteins. The researchers observed millions of segments of RNA changing shape in response to a chemical signal from an adenine molecule.

This groundbreaking observation was possible using SLAC's revolutionary X-ray free-electron lasers, capable of observing some of the quickest and most minuscule chemical and biological reactions. The results, which are published in Nature, open the door to a better understanding of RNA – the genetic material of retroviruses that also plays a role in most forms of cancer.

The particular biological switch is called a riboswitch and it is found only in bacteria. The international team of researchers looked at a specific one called Vibrio vulnificus, which is related to the bacterium that causes cholera.

The scientists believe that understanding the details on how the switch is activated could lead us to be capable of making the switch inactive, thus turning off protein production and killing harmful bacteria with no consequences to the infected humans.

The observations were not easy. X-rays are so powerful that they destroy molecules and so they are usually embedded in large crystals. RNA is too flexible for it to work like that, so the team has developed nanocrystals that allow them to catch the changes in RNA in a few millionths of a billionth of a second.

“Previous experiments at SLAC’s X-ray laser have studied biological reactions like photosynthesis that are triggered by light. But this is the first to observe one that is triggered by the chemical interaction of two biomolecules in real time and at the atomic scale,” said team leader Yun-Xing Wang, a structural biologist at the National Cancer Institute’s Center for Cancer Research, in a statement.

“This really demonstrates the unique capability that X-ray free-electron lasers offer that no current technology, or any other technology on the horizon, can do. It’s like you have a camera with a very fast shutter speed, so you can catch every move of the biomolecules in action.”