Download MendeleyA Stably Protonated Adenine Nucleotide with a Highly Shifted pKa Value Stabilizes the Tertiary Structure of a GTP-Binding RNA Aptamer.
Wolter, A.C., Weickhmann, A.K., Nasiri, A.H., Hantke, K., Ohlenschlager, O., Wunderlich, C.H., Kreutz, C., Duchardt-Ferner, E., Wohnert, J.(2017) Angew Chem Int Ed Engl 56: 401-404
- PubMed: 27885761
- DOI: https://doi.org/10.1002/anie.201609184
- Primary Citation of Related Structures:
5LWJ - PubMed Abstract:
RNA tertiary structure motifs are stabilized by a wide variety of hydrogen-bonding interactions. Protonated A and C nucleotides are normally not considered to be suitable building blocks for such motifs since their pK a values are far from physiological pH. Here, we report the NMR solution structure of an in vitro selected GTP-binding RNA aptamer bound to GTP with an intricate tertiary structure. It contains a novel kind of base quartet stabilized by a protonated A residue. Owing to its unique structural environment in the base quartet, the pK a value for the protonation of this A residue in the complex is shifted by more than 5 pH units compared to the pK a for A nucleotides in single-stranded RNA. This is the largest pK a shift for an A residue in structured nucleic acids reported so far, and similar in size to the largest pK a shifts observed for amino acid side chains in proteins. Both RNA pre-folding and ligand binding contribute to the pK a shift.
Organizational Affiliation:
Institut für Molekulare Biowissenschaften and Zentrum für Biomolekulare Magnetische Resonanz (BMRZ), Goethe-Universität Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt/Main, Germany.
