The glmS ribozyme-riboswitch is a gene-regulatory mRNA domain widely distributed in Gram-positive bacteria.  It controls expression of the mRNA encoding the protein enzyme glucosamine-6-phosphate (GlcN6P) synthetase.  GlcN6P binding to the riboswitch uncovers its latent self-cleavage activity, which leads to negative-feedback regulation of GlcN6P synthesis.  From the standpoint of RNA catalysis, use of GlcN6P as a cofactor is surprising because the glmS ribozyme is the only example among many known natural and artificial self-cleaving ribozymes that evolved to require a small organic molecule for function.  We hypothesized that the glmS ribozyme-riboswitch evolved from a closely related self-cleaving RNA that only required divalent cations for activity.  We found such an RNA by subjecting the glmS ribozyme to in vitro selection. In addition to suggesting a potential evolutionary ancestor to the glmS ribozyme, this work demonstrates that very few mutations can confer novel biochemical activities to RNAs with conserved structure.

Did the <i>glmS</i> ribozyme-riboswitch evolve from a coenzyme-independent self-cleaving RNA?

245th National Meeting (2013)

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Did the glmS ribozyme-riboswitch evolve from a coenzyme-independent self-cleaving RNA?