A mystery surrounding the way bacteria manage their vitamins piqued our interest in the fall of 2000. Together with growing evidence in support of a tantalizing theory about the earliest life on earth and our own efforts to build switches from biological molecules, the bacterial conundrum set our laboratory group at Yale University in search of an answer. What we found was a far bigger revelation than we were expecting: it was a new form of cellular self-control based on one of the oldest types of molecule around--ribonucleic acid, or RNA.

Long viewed as mostly a lowly messenger, RNA could have considerable authority, as it turned out, and sophisticated mechanisms for asserting it. Although the workings of this newfound class of RNA molecules that we dubbed riboswitches are still being characterized, it is already clear that they may also provide novel ways of fighting human diseases. Many pathogenic bacteria rely on riboswitches to control aspects of their own fundamental metabolism, for instance.