Open Dataset XSIEWNFS

SCOPER validation benchmark (RNA#6) SAM-I riboswitch RNA in presence of a SAM ligand


SCOPER is an efficient tool that can accurately predict the solution state of RNAs and provide an atomistic model of their structure. To validate SCOPER pipeline, we collected experimental SAXS data on a SAM-I riboswitch RNA in presence of a SAM ligand.

Experimental description

SAM-I riboswitch RNA preparation: The SAM-I RNA samples was prepared from in vitro T7 polymerase transcriptions reactions using PCR-generated DNA templates. The crude RNA was purified by 10%–12% denaturing gel electrophoresis as described. RNA samples were eluted from crushed gel slices overnight at 4°C into RNA storage buffer as described above. Chromatographic separations were performed with the Ettan LC liquid chromatography system (GE Healthcare) configured with a 3-wavelength ultraviolet-visual (UV-VIS) detector. Purifications were performed with Superdex 200 (SAM riboswitch) PC 3.2/2.4 mL column (GE Healthcare) in running buffer containing 20 mM MOPS at pH 6.5, 50 mM KCl, and 7.6 mM MgCl2. Purification of SAM-I was performed where the running buffer was supplemented with 100 μM SAM (Sigma-Aldrich). Flowthrough from each of the respective buffers was kept for buffer subtraction during SAXS analysis. Small-angle X-ray Scattering: SAXS experiments were performed at beamline 12.3.1 of the Advanced Light Source, Lawrence Berkeley National Laboratory. Twenty microliters of purified RNA samples and corresponding matching buffers were loaded into a 96-well plate (Nunc) and covered with protective film. RNA samples were collected at 2–3 mg/mL and diluted serial in the plate. Automated loading of the SAXS samples into the sample cuvette was achieved using a Hamilton syringe robot as described. For each sample, several exposures were taken using the following time sequence of 5, 50, and 5 sec or 6, 60, and 6 sec. All data collection was performed at room temperature. The first and last exposures of each sequence were compared to assess for radiation damage. Integration, scaling, and buffer subtraction was accomplished using the program Ogre (Greg Hura, Lawrence Berkeley National Laboratory). The scattering angle, q, was calculated as 4 π sin(θ/2)/λ where θ/2 is the scattering angle measured from the Bragg plane and λ is the wavelength in Å. A fixed detector distance was maintained at 1.486 m and with a wavelength of 1.03 Å (12,000 eV), and data were collected over the q range of 0.0088–0.322 Å−1.

File description SAM-I riboswitch SAXS curves for a concentration range between 1-3 mg/ml ; best_2gis_mg.dat : SCOPER SAXS fit; 2gis_original.pdb : SAM-I crystal structure; best_2gis_with_mg.pdb : SCOPER model





Data collection technique


Journal DOI




1.03 Å

Sample to Detector Distance

1.486 m

Submitting Author

Michal Hammel

Lawrence Berkeley National Laboratory, The SIBYLS Beamline

United States of America

[email protected]


Project Leader

Michal Hammel

[email protected]

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Complete Set of SAS Data Files

The complete SAS dataset is downloadable as a zip file.

Individual SAS Data Files (total 1)

These are individual SAS data files that may be raw or processed (merged, etc.). These may or not be included in a zip file containing a larger dataset.

Supplemental Data and Supporting Materials (total 2)

These data and materials may include X-ray crystal structure coordinates, multi-angle light scattering data, .etc. It may also include additional details or methods pertaining to the SAXS experiments, or the researcher's interpretations of the results.

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SAXS Similarity SAXS FrameSlice


  • Macromolecule 1: SAM-I RNA
    • Sample Full Name: SAM-I riboswitch RNA
    • Sample Type: RNA
    • Source Organism: Homo Sapiens
    • Source Organism NCBI Taxonomy ID: 9606
    • Expression System:
    • Expression NCBI Taxonomy ID:
    • Uniprot ID:
    • Sequence or Chemical Formula: