Fig. 5. Multiple locations across the OmpX sequence interact with similar sites on SurA.

a Tag-transfer photo-cross-linking⁴⁸ of SurA-OmpX complexes using OmpX Cys variants labelled with MTS-diazirine analysed by SDS-PAGE. A band corresponding to the SurA-OmpX complex is observed for all OmpX variants following UV irradiation. These bands were not observed when analysed using reducing SDS-PAGE (Supplementary Fig. 8b). Source data are provided as a Source Data file. b Inter-molecular cross-links detected in the SurA-OmpX complex (Supplementary Table 8). c Structure of SurA with residues which were photo-cross-linked to labelled OmpX Cys variants shown in purple. Where the data quality did not permit residue level assignment, the cross-linked peptide is shown in light purple. Samples contained 10 μM SurA, 5 µM MTS-diazirine-labelled OmpX, 0.24 M urea, in 10 mM potassium phosphate buffer, pH 8.0, 25 °C and cross-linking was initiated by UV LED irradiation of the sample for 30 s (see Methods). A representative mass spectrum for each cross-link can be found in Supplementary Data 1.