If you want to watch where and how a protein moves, you can purify it, attach fluorescent dye tags, and then use laser light to kick the dyes into lighting up under a microscope. But what if you want to watch a dozen proteins interact? Or a hundred?
Aaron Hoskins and other researchers at Brandeis University, University of Massachusetts Medical School, and Columbia University took on the challenge to watch the molecular machine that assembles pre-messenger RNA, snipping out non-protein-coding areas of RNA and splicing together the ends. It’s a complex process that involves so many proteins that purification is impractical. Instead, they used genetic engineering and chemical biology to change the yeast DNA to incorporate small dye molecules right into the proteins. And they watched the gene splicing process in real time using a three-color laser fluorescence microscopy system shown in the picture.
The neat thing is that this method can be used to learn more about a lot of the molecular machines that self-assemble, do fairly complicated tasks, and then fall apart again in our cells.
Their paper in Science: Ordered and Dynamic Assembly of Single Spliceosomes
Brandeis has more on the story as well: Lasers, custom microscope illuminate gene splicing .