We all know that fluoride plays the leading role in toothpastes and mouthwashes everywhere. “4 out of 5 dentists recommend it,” after all. It fights plaque buildup and cavities but new studies are showing just how much of a power hitter fluoride really is.
Researchers led by Ron Breaker at Yale University report their new understandings about the way in which bacteria and fluoride actually interact, published online in Science Express on December 22, 2011. Even though this was reportedly an accident, we’ll give them due credit anyway.
Fluoride is a naturally occurring element in the Earth’s crust which eventually finds its’ way to our drinking water. In this way, Bacteria have been fighting fluoride for a long time.
“Cells have had to contend with fluoride toxicity for billions of years, and so they have evolved precise sensors and defense mechanisms to do battle with this ion,” says Breaker. “Now that these sensors and defense mechanisms are known, it may be possible to manipulate these mechanisms and make fluoride even more toxic to bacteria.”
These sensors, sections of RNA messages called riboswitches, control the expression of genes. When riboswitches in bacteria detect build-ups of fluoride they “switch on” activating the defenses including those that contribute to tooth decay. “If fluoride builds up to toxic levels in a cell, a fluoride riboswitch grabs the fluoride and then turns on genes that can overcome its’ effects,” said Breaker.
“We were stunned when we uncovered fluoride-sensing riboswitches,” says Breaker. “Scientists would argue that RNA is the worst molecule to use as a sensor for fluoride, and yet we have found more than 2000 of these strange RNAs in many organisms.”
So, how were these findings an accident? Well, like donuts and Teflon, serendipitous accidents sometimes make the best breakfasts. Er, discoveries.
Breaker’s team had stumbled upon the riboswitch but as it was attached to just a few genes with largely vague and unknown functions, they were baffled. “We knew we had a riboswitch but we didn’t know what it bound,” says Breaker, “and we were very intrigued because it was one of the only non-coding RNA’s we’ve ever found that’s present in both bacteria and archaea. That suggests that it has ancient origins and an important role in the cell.”
So the team at Yale began experimenting with different chemical combinations looking for one that would bind with the riboswitch. After a long list of common chemicals, fluoride was the accident. It was actually a contaminant in the sample of another chemical they were testing.