In 1999 we discovered LuxS, an enzyme needed for making a signal molecule (AI-2) that bacteria use for interspecies communication.1 X-ray crystallography allowed us to see that AI-2 is composed of two, five-membered rings. The challenge was to determine which atoms composed the rings. Our initial guess, a mixture of carbons and oxygens, appalled our chemist friends: we had drawn a carbon atom covalently bonded to four oxygens! After months of puzzling, we thought to replace that carbon with a boron atom. Later the same day, we tested whether addition of boron to bacteria would allow them to produce extra AI-2. The scintillation printout from that day charts bacteria responding to the AI-2 signal. Compared to control experiments, the measurements at the bottom left reflect a dramatic increase in AI-2 production when more boron is available. Our discovery was among the first to show boron in a biological molecule."
--Bonnie ...
