The yybP-ykoY leaderRNA element was originally discovered in E. coli during a large scale screen and was named SraF. This family was later found to exist upstream of related families of protein genes in many bacteria, including the yybP and ykoY genes in B. subtilis. The specific functions of these proteins are unknown, but this structured RNA element may be involved in their genetic regulation as a riboswitch. The yybP-ykoY element was later proposed to be manganese-responsive after another associated family of genes, YebN/MntP, was shown to encode Mn2+ efflux pumps in several bacteria. Genetic data and a crystal structure confirmed that yybp-ykoY is a manganese riboswitch that directly binds Mn2+
^Veyrier, FJ; Boneca, IG; Cellier, MF; Taha, MK (Sep 2011). "A novel metal transporter mediating manganese export (MntX) regulates the Mn to Fe intracellular ratio and Neisseria meningitidis virulence". PLoS Pathog. 8 (9): e1002261. doi:10.1371/journal.ppat.1002261.
^Price, IR; Gaballa, A; Ding, F; Helmann, JD; Ke, A (19 March 2015). "Mn2+-Sensing Mechanisms of yybP-ykoY Orphan Riboswitches". Mol Cell. 57 (6): 1110–1123. doi:10.1016/j.molcel.2015.02.016.