Structural and mechanistic characterization of a bacterial catalytic riboswitch

CHED 955

Juliane Soukup, jksoukup@creighton.edu and Kevin Klawuhn, KevinKlawuhn@creighton.edu. Department of Chemistry, Creighton University, 2500 California Street, Omaha, NE 68178
Riboswitches can directly bind metabolites and undergo structural modulations in order to control gene expression. The glmS riboswitch is a ribozyme that undergoes self-cleavage when bound by its metabolite glucosamine-6-phosphate (GlcN6P). Our research has focused on assessing the mechanistic strategies employed by the ribozyme and its interaction with ligand during both folding and catalysis. We estimate that prefolding the ribozyme with Mg2+ results in a substantial rate enhancement. The significance of Mg2+ binding and interaction with ligand has been further investigated using other metal ion cofactors found to activate ribozyme cleavage. In addition, we have previously determined that the protonation state of the ligand amine group of GlcN6P affects catalysis. Further analyses, utilizing a number of ligand analogs, continue to investigate the role of the amine group in catalysis.