Scientists were already embracing RNAi-based tools to manipulate cells by destroying specific RNA molecules. “The fact that CRISPR was destroying DNA opened up a completely different set of possibilities,” Marraffini explains.
Soon after, Marraffini collaborated with Feng Zhang at the Broad Institute of MIT and Harvard to demonstrate that CRISPR could be put to work editing genes in cells other than bacteria. Research into CRISPR exploded, and the system was quickly developed into the most precise and efficient tool that biologists now have for manipulating genomes.
Marraffini is thrilled to have been a part of this technological revolution. “But what I do best, and what I like to do most, is study bacteria,” he says.
His lab at the Rockefeller University is dedicated to understanding how bacteria use CRISPR. Six different types of CRISPR systems have now been discovered, and Marraffini wants to know why they’re so diverse. They all seem to protect against foreign invaders, but they use very different mechanisms to do so. Marraffini suspects that’s because bacteria-infecting viruses are one of the most diverse life-forms on earth. Microbes that encounter different threats may need different strategies to deal with them.