Plasmonic nanosensors reveal a height dependence of MinDE protein oscillations on membrane features

Abstract

Single-particle plasmon spectroscopy has become a standard technique todetect and quantify the presence of unlabeled macromolecules. Here, we extend thismethod to determine their exact distance from the plasmon sensors with sub-nanometerresolution by systematically varying the sensing range into the surrounding by adjustingthe size of the plasmonic nanoparticles. We improved current single-particle plasmonspectroscopy to record continuously for hours the scattering spectra of thousands ofnanoparticles of different sizes simultaneously with 1.8 s time resolution. We apply thistechnique to study the interaction dynamics of bacterial Min proteins with supportedlipid membranes of different composition. Our experiments reveal a surprisinglyflexibleoperating mode of the Min proteins: In the presence of cardiolipin and membranecurvature induced by nanoparticles, the protein oscillation occurs on top of a stationaryMinD patch. Our results reveal the need to consider membrane composition and localcurvature as important parameters to quantitatively understand the Min protein system and could be extrapolated to othermacromolecular systems. Our label-free method is generally easily implementable and well suited to measure distances ofinteracting biological macromolecules