PreQ1-II riboswitches form a class of riboswitches that specifically bind pre-queuosine<sub>1</sub> (PreQ<sub>1</sub>), a precursor of the modified nucleoside queuosine. They are found in certain species of Streptococcus and Lactococcus, and were originally identified as a conserved RNA secondary structure called the "COG4708 motif". All known members of this riboswitch class appear to control members of COG4708 genes. These genes are predicted to encode membrane-bound proteins and have been proposed to be a transporter of preQ<sub>1</sub>, or a related metabolite, based on their association with preQ<sub>1</sub>-binding riboswitches. PreQ1-II riboswitches have no apparent similarities in sequence or structure to preQ1-I riboswitches, a previously discovered class of preQ<sub>1</sub>-binding riboswitches. PreQ<sub>1</sub> thus joins S-adenosylmethionine as the second metabolite to be found that is the ligand of more than one riboswitch class.