Structure and dynamics of the deoxyguanosine-sensing riboswitch studied by NMR-spectroscopy
The mfl-riboswitch regulates expression of ribonucleotide reductase subunit in Mesoplasma florum by binding to 2´-deoxyguanosine and thereby promoting transcription termination. We characterized the structure of the ligand-bound aptamer domain by NMR spectroscopy and compared the mfl-aptamer to the aptamer domain of the closely related purine-sensing riboswitches. We show that the mfl-aptamer accommodates the extra 2´-deoxyribose unit of the ligand by forming a more relaxed binding pocket than these found in the purine-sensing riboswitches. Tertiary structures of the xpt-aptamer bound to guanine and of the mfl-aptamer bound to 2´-deoxyguanosine exhibit very similar features, although the sequence of the mfl-aptamer contains several alterations compared to the purine-aptamer consensus sequence. These alterations include the truncation of a hairpin loop which is crucial for complex formation in all purine-sensing riboswitches characterized to date. We further defined structural features and ligand binding requirements of the free mfl-aptamer and found that the presence of Mg2+ is not essential for complex formation, but facilitates ligand binding by promoting pre-organization of key structural motifs in the free aptamer.
|Author:||Anna Wacker, Janina Buck, Daniel Mathieu, Christian Richter, Jens Wöhnert, Harald Schwalbe|
|Date of Publication (online):||13.08.2011|
|Year of first Publication:||2011|
|Publishing Institution:||Univ.-Bibliothek Frankfurt am Main|
|Source:||Nucleic acids resarch, 39, doi: 10.1093/nar/gkr238|
|Dewey Decimal Classification:||570 Biowissenschaften; Biologie|
© The Author(s) 2011. 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/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
|Licence (German):||Creative Commons - Namensnennung-Nicht kommerziell 3.0|