Fig. 1: LecA-induced SLB reorganization visualized by fluorescence microscopy.

The SLB was labeled by HPC-Bodipy that localized to Ld domains (cyan). LecA was labeled with Cy5 (red). a Time series of LecA interaction with a phase-separated SLB (DOPC/chol/SM/Gb3 (37.5/20/37.5/5)). LecA bound mainly to Lo domains (black arrowhead, as one example), induced the dispersion of Lo domains (blue arrowheads) and later the formation of membrane multilayers (pink arrowheads). At around 5 min, LecA started to form clusters (white arrowheads) that colocalized with membrane multilayers. At later time points of incubation, large membrane defects appeared (orange arrowheads). Photobleaching of the fluorophore Cy5 coupled to LecA in membrane multilayers can be observed at later time points (30 min—white arrowheads). The alternative explanation would be the localization of LecA to the edges of multilayers at late time points. The complete time sequence is available online as Supplementary Movie 1. b Changes of the total area of Lo domains, membrane defects, and membrane multilayers over time for the bilayer depicted in (a). c Changes of the total number of Lo domains over time for the SLB depicted in (a). d Changes of the sizes of the individual Lo domains over time. The number of Lo domains is displayed in brackets. e Intensity histograms of the full image at different timepoints, dashed vertical lines depict how different membranes were recognized by intensity. f Intensity profiles extracted along the dashed white lines as depicted in (a), HPC-Bodipy channel. Dashed horizontal black lines depict how different membranes were recognized by intensity. g The mean fluorescence intensity of HPC-Bodipy in membrane multilayers (recorded at 15 min after LecA application) was ~1.36 times higher than the intensity of the original, single-bilayer membrane. All quantifications are provided for the single image displayed in (a). Scale bars are 10 µm (for full image) and 5 µm (for zoom).