Synchrotron SAXS
data from solutions of
TAF1 tandem bromodomain with inhibitor BAY299
in
50 mM HEPES, 5% v/v ethylene glycol, 2.5% v/v DMSO and 2 mM DTT, pH 7.5
were collected
on the
BioCAT 18ID beam line
at the Advanced Photon Source (APS), Argonne National Laboratory storage ring
(Lemont, IL, USA)
using a Pilatus3 X 1M detector
at a sample-detector distance of 3.5 m and
at a wavelength of λ = 0.10332 nm
(I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle).
One solute concentration of 1.50 mg/ml was measured
at 25°C.
1900 successive
0.500 second frames were collected.
The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.
Experiments were conducted at room temperature in 50 mM HEPES (pH7.5), 5% v/v ethylene glycol, 2.5% v/v DMSO and 2 mM DTT. Ab initio shape models of TAF1-T were generated using DENSS for electron density map generation and bead modeling by DAMMIN. Multiple runs were performed to generate 20 starting models, and the final ab initio shape was reconstructed by averaging and refining the starting models. The low-resolution electron density maps generated by DENSS and the bead models computed by DAMFILT of the ATSAS suit are shown in the associated publication. Isolated models of BD1 and BD2 omitting flexible regions of the N- and C-termini (1371 -1376 and 1631 – 1635) served for rigid body fitting into the electron density maps using PHENIX (dock_in_map) and Chimera. The hinge region connecting the two domains was modeled using ModLoop49. Iterative refinement cycles were applied using Crysol 3.0 to achieve models that satisfied the experimental data.
s, nm-1
