Dissecting the influence of Mg2+ on 3D architecture and ligand-binding of the guanine-sensing riboswitch aptamer domain

  • Long-range tertiary interactions determine the three-dimensional structure of a number of metabolite-binding riboswitch RNA elements and were found to be important for their regulatory function. For the guanine-sensing riboswitch of the Bacillus subtilis xpt-pbuX operon, our previous NMR-spectroscopic studies indicated pre-formation of long-range tertiary contacts in the ligand-free state of its aptamer domain. Loss of the structural pre-organization in a mutant of this RNA (G37A/C61U) resulted in the requirement of Mg2+ for ligand binding. Here, we investigate structural and stability aspects of the wild-type aptamer domain (Gsw) and the G37A/C61U-mutant (Gswloop) of the guanine-sensing riboswitch and their Mg2+-induced folding characteristics to dissect the role of long-range tertiary interactions, the link between pre-formation of structural elements and ligand-binding properties and the functional stability. Destabilization of the long-range interactions as a result of the introduced mutations for Gswloop or the increase in temperature for both Gsw and Gswloop involves pronounced alterations of the conformational ensemble characteristics of the ligand-free state of the riboswitch. The increased flexibility of the conformational ensemble can, however, be compensated by Mg2+. We propose that reduction of conformational dynamics in remote regions of the riboswitch aptamer domain is the minimal pre-requisite to pre-organize the core region for specific ligand binding.

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Author:Janina BuckGND, Jonas Noeske, Jens WöhnertORCiDGND, Harald SchwalbeORCiDGND
Parent Title (English):Nucleic acids research
Document Type:Article
Date of Publication (online):2010/11/11
Year of first Publication:2010
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2010/11/11
First Page:4143
Last Page:4153
© The Author(s) 2010. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.5), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Source:Nucleic acids research (2010) 38 (12): 4143-4153 ; doi: 10.1093/nar/gkq138
Institutes:Biochemie, Chemie und Pharmazie / Biochemie und Chemie
Biowissenschaften / Biowissenschaften
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Sammlung Biologie / Sondersammelgebiets-Volltexte
Licence (German):License LogoDeutsches Urheberrecht