Fig. 2: SAXS analysis of the N-terminal domain of BTSL2.

a Expression construct of the Arabidopsis BTSL2 N-terminus (BTSL2-N, codons 1 – 831) encompassing the three Hr-like sequences, flanked by Maltose Binding Protein (MBP) for solubility and a C-terminal Strep tag for affinity purification. b Coomassie-stained SDS-PAGE gel of MBP-BTSL2-N purified using Strep-Tactin XT (left) and of BTSL2-N after removal of the MBP domain following protease Xa cleavage and size-exclusion chromatography (right). The images are representative of three experiments. c Scattering profile of intensity I(q), presented in log-scale, versus q, the momentum transfer variable which is inversely correlated with the X-ray wavelength in Ångstrom (Å⁻¹). Inset: Guinier analysis, in which ln(I) is plotted against q². A radius of gyration Rg of 33.95 ± 0.05 Å was calculated from the slope of the graph (R² = 0.9941). The intensity at zero angle I(0) was 0.062 cm⁻¹ ± 0.000096 and the residual values showed an even distribution. d Model of the BTSL2-N protein envelope overlaid with a refined AlphaFold2 model with manually inserted diiron centres. See Supplementary Data 1 for a summary of SAXS experimental data and analysis. Source data have been deposited under accession SASDU79 in www.sasbdb.org.