Co-crystal structure of the iMango-III fluorescent RNA aptamer using an X-ray free-electron laser

Turn-on aptamers are in vitro-selected RNAs that bind to conditionally fluorescent small molecules and enhance their fluorescence. Upon binding TO1-biotin, the iMango-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 iMango-III have previously been determined by conventional cryocrystallography using synchrotron X-radiation. Using an X-ray free-electron laser (XFEL), the room-temperature iMango-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.
Source: Acta Crystallographica Section F - Category: Biochemistry Authors: Tags: RNA structure fluorescence turn-on aptamers X-ray free-electron lasers iMango-III XFELS room temperature research communications Source Type: research