A genetic disruption strategy developed by CU Boulder researchers effectively stymies the evolution of antibiotic-resistant bacteria such as听E. coli, giving scientists a crucial leg up in the ongoing battle against deadly superbugs.
These multidrug-resistant pathogens鈥攚hich adapt to current antibiotics faster than new ones can be created鈥攊nfect nearly 2 million people and cause at least 23,000 deaths annually in the U.S., according to data from the听.听
In an effort to develop a sustainable long-term solution, CU Boulder researchers created the听Controlled Hindrance of Adaptation of OrganismS (CHAOS)听approach, which uses CRISPR DNA editing techniques to modify multiple gene expressions within the bacteria cells, stunting the pathogen鈥檚 central processes and thwarting its ability to evolve defenses.
The findings are 听and could open new research avenues on how to best restrict a pathogen鈥檚 antibiotic resistance.
鈥淲e now have a way to cut off the evolutionary pathways of some of the nastiest bugs and potentially prevent future bugs from emerging at all,鈥� said Peter Otoupal, lead author of the study and a doctoral researcher in CU Boulder鈥檚听Department of Chemical and Biological Engineering (CHBE).
The CHAOS research is the culmination of work that began in 2013, when Otoupal and his colleagues began searching for genes that could act as a cellular kill switch for听E. coli. When the scientists tweaked one gene at a time, the bacteria could adapt and survive. But when they altered two or more genes at once, the cell got weaker.
鈥淲e saw that when we tweaked multiple gene expressions at the same time鈥攅ven genes that would seemingly help the bacteria survive鈥攖he bacteria鈥檚 fitness dropped dramatically,鈥� Otoupal said.
The CHAOS method takes advantage of this effect, pulling multiple genetic levers in order to build up stress on the bacterial cell and eventually trigger a cascading failure, leaving the bug more vulnerable to current treatments. The technique does not alter the bug鈥檚 DNA itself, only the expression of individual genes, similar to the way a coded message is rendered useless without the proper decryption.
鈥淵ou can think of it in terms of a series of escalating annoyances to the cell that eventually cause it to weaken,鈥� said Anushree Chatterjee, senior author of the study and an assistant professor in CHBE. 鈥淭his method offers tremendous potential to create more effective combinatorial approaches.鈥�
Although听E. coli听has nearly 4,000 individual genes, the exact gene modification sequence appears to matter less than the sheer number of genes that are disrupted, Otoupal said. Still, the researchers plan to continue optimizing the CHAOS method to seek out the most efficient disruptions.鈥淒iseases are very dynamic, so we need to design smarter therapies that can gain control over their rapid adaptation rates,鈥� Chatterjee said. 鈥淭he emphasis in our lab is demonstrating the efficacy of these methods and then finding ways to translate the technology to modern clinical settings.鈥�
鈥淚n the past, nobody really considered that it might be possible to slow down evolution,鈥� Otoupal said. 鈥淏ut like anything else, evolution has rules and we鈥檙e starting to learn how to use them to our advantage.鈥�
CHBE researchers William Cordell, Vismaya Bachu and Madeleine Sitton co-authored the new study. The National Science Foundation, the William M. Keck Foundation, the Defense Advanced Research Projects Agency (DARPA) and CU Boulder provided funding for the research.
