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Co‐crystal structure of the i Mango‐III fluorescent RNA aptamer using an X‐ray free‐electron laser
Author(s) -
Trachman Robert J.,
Stagno Jason R.,
Conrad Chelsie,
Jones Christopher P.,
Fischer Pontus,
Meents Alke,
Wang Yun-Xing,
Ferré-D'Amaré Adrian R.
Publication year - 2019
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x19010136
Subject(s) - fluorescence , electron , x ray , aptamer , rna , laser , free electron model , free electron laser , optics , materials science , crystallography , physics , chemistry , biology , microbiology and biotechnology , nuclear physics , biochemistry , gene
Turn‐on aptamers are in vitro ‐selected RNAs that bind to conditionally fluorescent small molecules and enhance their fluorescence. Upon binding TO1‐biotin, the i Mango‐III aptamer achieves the largest fluorescence enhancement reported for turn‐on aptamers (over 5000‐fold). This aptamer was generated by structure‐guided engineering and functional reselection of the parental aptamer Mango‐III. Structures of both Mango‐III and i Mango‐III have previously been determined by conventional cryocrystallography using synchrotron X‐radiation. Using an X‐ray free‐electron laser (XFEL), the room‐temperature i Mango‐III–TO1‐biotin co‐crystal structure has now been determined at 3.0 Å resolution. This structural model, which was refined against a data set of ∼1300 diffraction images (each from a single crystal), is largely consistent with the structures determined from single‐crystal data sets collected at 100 K. This constitutes a technical benchmark on the way to XFEL pump–probe experiments on fluorescent RNA–small molecule complexes.