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

ABSTRACT: 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.

SUBMITTER: Trachman RJ 

PROVIDER: S-EPMC6688663 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature