Extended Data Fig. 10: LtaA-catalyzed lipid-linked-disaccharide flipping and proton gradients.
From: Structure of a proton-dependent lipid transporter involved in lipoteichoic acids biosynthesis
a, Representative traces of flipping assays with a control transporter (bacterial choline transporter) in the presence of different proton gradients, in and out denote pH of buffer inside and outside of liposomes, respectively (n ≥ 3). Asterisk marks addition of dithionite. F correspond to the fluorescence intensity measured for each time point. Fmax is the average fluorescence measured during the first 200 seconds. b, Scheme of LtaA-catalyzed lipid-linked-disaccharide flipping under an outward proton gradient (top), no gradient (center), and an inward proton gradient (bottom). Under application of a pH gradient (∇H+), LtaA (yellow boxes) translocates NBD-anchor-LLD (red spheres) contrary to the proton gradient. Addition of dithionite (dit.) then reduces exposed and exchanged NBD-anchor-LLD (black spheres). The extent of quenching is in accordance to the direction of the pH gradient. Full fluorescence quenching will be achieved after prolonged incubation (dashed arrows).
