Synchrotron SAXS data from solutions of the ESX-1 secretion-associated protein EspB (medium construct) in 20 mM Tris-HCl, 300 mM NaCl, pH 8 were collected on the EMBL P12 beam line at PETRA III (DESY, 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: A 50.00 μl sample at 6.7 mg/ml was injected at a 0.08 ml/min flow rate onto a GE Superdex 200 Increase 5/150 column at 20°C. 900 successive 1 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.