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Journal/Book: ChemBioChem
Published: 2006
Pages: 1451–1456
Volume: 7
Accession no.: 124

Phosphate-group recognition by the aptamer domain of the thiamine pyrophosphate sensing riboswitch.

Jonas Noeske, Christian Richter, Elke Stirnal, Harald Schwalbe, Jens Wöhnert
Riboswitches are highly structured RNA elements that control gene expression by binding directly to small metabolite molecules. Remarkably, many of these metabolites contain negatively charged phosphate groups that contribute significantly to the binding affinity. An example is the thiamine pyrophosphate-sensing riboswitch in the 5'-untranslated region of the E. coli thiM mRNA. This riboswitch binds, in order of decreasing affinity, to thiamine pyrophosphate (TPP), thiamine monophosphate (TMP), and thiamine, which contain two, one, and no phosphate groups, respectively. We examined the binding of TPP and TMP to this riboswitch by using (31)P NMR spectroscopy. Chemical-shift changes were observed for the alpha- and beta-phosphate group of TPP and the phosphate group of TMP upon RNA binding; this indicates that they are in close contact with the RNA. Titration experiments with paramagnetic Mn(2+) ions revealed strong line-broadening effects for both (31)P signals of the bound TPP; this indicates a Mg(2+) binding site in close proximity and suggests that the phosphate group(s) of the ligand is/are recognized in a magnesium ion-mediated manner by the RNA.
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Prof. Dr. Harald Schwalbe
Institut für Organische Chemie und Chemische Biologie
Johann Wolfgang Goethe Universität
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D-60438 Frankfurt am Main
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