Fig. 2. Comparison of the catalytic activity of BAM in proteoliposomes and nanodiscs.

a Fluorescence detected from cleavage of a fluorescent OmpT substrate in BAM-containing proteoliposomes (red), BAM in MSPE3D1 (blue) or MSP1D1 nanodiscs (green), empty nanodiscs (purple and dark green for MSPE3D1 and MSP1D1, respectively) and empty liposomes (i.e. lacking BAM) (yellow). For each sample, the coloured line represents the mean fluorescence, whilst grey lines represent the minimum and maximum values for three replicates. b Gel shift assay measuring BAM-catalysed folding of tOmpA. Folded tOmpA is indicated by red arrows, whilst a contaminating band, present in all samples, is marked with a red asterisk. In this assay, tOmpA is labelled with Alexa Fluor 488, enabling the folding of the substrate to be visualised using fluorescence detection, without interference from protein bands arising from BamABCDE and SurA.