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Ligand Recognition Mechanism of Thiamine Pyrophosphate Riboswitch Aptamer
Author(s) -
Uhm Heesoo,
Hohng Sungchul
Publication year - 2017
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.11328
Subject(s) - riboswitch , aptamer , förster resonance energy transfer , chemistry , ligand (biochemistry) , thiamine pyrophosphate , biophysics , rna , fluorescence , biochemistry , cofactor , biology , non coding rna , gene , microbiology and biotechnology , receptor , physics , enzyme , quantum mechanics
Riboswitches regulate gene expression by coupling ligand binding to a structural transition of the riboswitch, but the coupling mechanism is still controversial. We addressed this issue by characterizing both the ligand‐free state of the Escherichia coli thiamine pyrophosphate (TPP) riboswitch aptamer and its structural transition upon ligand binding using single‐molecule fluorescence resonance energy transfer (FRET). Our results reveal that the apo‐aptamer dynamically samples a partially closed form resembling the holo‐aptamer, but TPP binding occurs in both the open and partially closed forms with the same efficiency. Mutation studies reveal that the preformation of the aptamer secondary structure is critical for TPP binding, and that tertiary interaction is established after TPP binding.