Synchrotron SAXS data from solutions of AtaC in 20 mM HEPES, 200mM NaCl, pH 7.5 were collected on the EMBL P12 beam line at PETRA III (Hamburg, Germany) using a Pilatus 6M detector at a sample-detector distance of 3 m and at a wavelength of λ = 0.124 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). In-line size-exclusion chromatography (SEC) SAS was employed. The SEC parameters were as follows: 75 μl of an 8 mg/ml sample were injected onto a GE Superdex 200 Increase 10/300 column at 20°C (0.6 ml/min flow rate). 2400 successive 1 second frames were collected through the entire SEC run. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted from those data frames corresponding to the sample elution peak.