Roles of Mg2+ in TPP-dependent riboswitch

AbstractWe quantified the effect of Mg2+ on thiamine pyrophosphate (TPP) binding to TPP-dependent thiA riboswitch RNA. The association constant of TPP binding to the riboswitch at 20°C increased from 1.2×106 to 50×106M−1 as the Mg2+ concentration increased from 0 to 1mM. Furthermore, circular dichroic spectra under various conditions showed that 1mM Mg2+ induced a local structural change of the riboswitch, which might be pivotal for TPP binding. These results indicate that a physiological concentration of Mg2+ can regulate TPP binding to the thiA riboswitch