Recruitment of receptors at supported lipid bilayers induced by strong and weak multivalent binding Jurriaan Huskens , Daniele Di Iorio, Yao Lu, Joris Meulman, Giulia Allegri University of Twente, Netherlands The development of model systems that mimic biological interactions and allow the control of both receptor and ligand densities, is essential for a better understanding of biomolecular processes, such as the recruitment of receptors at interfaces, at the molecular level. Here we report a model system based on supported lipid bilayers (SLBs) for the investigation of the clustering of receptors at their interface (Figure 1). Biotinylated SLBs, used as cell membrane mimics, were functionalized with streptavidin (SAv), used here as an initial receptor. Subsequently, biotinylated small (SUVs) and giant (GUVs) unilamellar vesicles were bound to the SAv-functionalized SLBs by multivalent interactions and found to induce the recruitment of both SAv on the SLB surface and the biotin moieties in the vesicles [1]. The recruitment of receptors was investigated with quartz crystal microbalance with dissipation monitoring (QCM-D), which allowed the identification of the biotin and SAv densities necessary to obtain receptor recruitment. At approx. 0.6% of biotin in the vesicles, a transition between dense and low vesicle packing was observed, which coincided with the transitions between recruitment in the vesicles vs. recruitment in the SLB and between full and partial use of the biotin moieties in the vesicle.1 Direct optical visualization of the clustering at the interface of individual GUVs with the SLB platform was achieved with fluorescence microscopy, showing recruitment of SAv at the contact area as well as the deformation of the vesicles upon binding. Different vesicle binding regimes were observed for lower and higher biotin densities in the vesicles and at the SLBs. A more quantitative analysis of the molecular parameters implied in the interaction, indicated that approx. 10% of the vesicle area constitutes the contact area. In a follow-up system, we used biotinylated receptors on the SAv SLBs and complementary groups at the vesicles as a weak interaction motif. We compare these strong and weak binding multivalent systems in their ability to show receptor recruitment [2]. The mechanisms revealed in this study may provide insight in biological processes in which recruitment occurs. References 1. D. Di Iorio, Y. Lu, J. Meulman, J. Huskens, Chemical Science 2020 , 11 , 3307. Y. Lu, G. Allegri, J. Huskens, submitted .
SM05
© The Author(s), 2023
Made with FlippingBook Learn more on our blog