While preQ1 was first discovered as an anticodon sequence of tRNAs from E.coli in 1972,[REF] preQ1 riboswitch was not first found until 2004[REF] and recognized even later [REF].
In 2008, a second class of preQ1 riboswitch (PreQ1-II riboswitches) was also found as a representative of the COG4708 RNA motif from Streptococcus pneumoniae R6 [REF].