Fluoride ion encapsulation by Mg2+ ions and phosphates in a fluoride riboswitch

Article

关键词: THIAMINE PYROPHOSPHATE RIBOSWITCH;    BACTERIAL GENE-EXPRESSION;    STRUCTURAL BASIS;    GLYCINE RIBOSWITCH;    MESSENGER-RNAS;    LIGAND;    RECOGNITION;    DOMAIN;    MOLECULES;    MECHANISM;   

DOI  :  10.1038/nature11152

来源: SCIE

【 摘 要 】

Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A.U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg2+ ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.

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