Spherical nanoparticle supported lipid bilayers for the structural study of membrane geometry-sensitive molecules

Abstract

Many essential cellular processes including endocytosis and vesicle trafficking require alteration of membrane geometry. These changes are usually mediated by proteins that can sense and/or induce membrane curvature. Using spherical nanoparticle supported lipid bilayers (SSLBs), we characterize how SpoVM, a bacterial development factor, interacts with differently curved membranes by magic angle spinning solid-state NMR. Our results demonstrate that SSLBs are an effective system for structural and topological studies of membrane geometry-sensitive molecules.

Figure 1

SSLB representation.

Figure 2

Curvature-dependent membrane insertion depth. (a) 1D 500 MHz ¹H HRMAS spectrum of DMPC-coated 1 μm SSLBs recorded at 30 °C, 10 kHz spinning speed. STD factors of SpoVM (red) and SpoVM^R17D (blue) bound to DMPC-coated (b) 1 μm SSLBs at a molar ratio of 1:100. (c) 100 nm SSLBs at a molar ratio of 1:280.

Figure 3

Structure validations of SpoVM and SpoVM^P9A in SSLBs. 2D MAS ¹³C–¹³C correlation spectra for ¹³C-,¹⁵N-labeled SpoVM (a) and SpoVM^P9A (b) bound to DMPC-coated 50 nm SSLBs. The data were collected on an 800 MHz Bruker NMR instrument with 35 ms mixing time,10 kHz spinning speed, 1.5 s recycle delay at 15 °C (sample temperature) for increased spectral sensitivity. The total acquisition time was about 36 h. Temperature-dependent static ³¹P NMR spectra indicate no lipids are detached from these SSLBs to form small discoidal structures in the gel phase (Figure S4).