Fig. 4: Di-LecA-induced SLB reorganization visualized by fluorescence microscopy.

The SLB was labeled by HPC-Bodipy that localized into Ld domains (cyan). Di-LecA was labeled by Cy5 (red). Images were acquired with wide-field microscopy (HILO). a Time series of Di-LecA interactions with phase-separated SLB (DOPC/chol/SM/Gb3 (37.5/20/37.5/5)). Di-LecA bound preferentially to Lo domains and induced fusion and a decrease in size of the Lo domains (pink arrowhead). b Decrease of the total area and number of Lo domains over time. c The sizes of the individual Lo domains (numbers of Lo domains are indicated) slightly decreased over time; d, e Contrast of the fluorescence signal between the Ld and Lo domains at different time points. d HPC-Bodipy fluorescence intensity profile along the white line displayed in (a) at different time points. e Intensity contrast (ratio between the fluorescence intensity signals of HPC-Bodipy in Ld and Lo domains) value at different time points for all Lo domains. After 1 h, the contrast dropped to about half of the initial value. This suggests a so-called asymmetric Lo domain dispersion (i.e., Lo domains disperse only in the upper lipid monolayer whereas in the bottom monolayer, they remain intact). The scale bars are 10 and 5 µm, respectively. The complete time sequence is available online as Supplementary Movie 5. All quantifications are provided for the single image displayed in (a).