A. Lipoteichoic acid synthesis pathway in Staphylococcus aureus
5. YpfP synthesizes the LTA anchor-LLD on the cytoplasmic leaflet of the membrane, LtaA performs anchor-LLD flipping towards the extracellular side of the membrane where the LtaS polymerase assemble the 1,3-glycerol-phosphate polymer on anchor-LLD. The structure of the periplasmic domain of LtaS (PDB: 4UOO)22 is shown. PG: Phosphatidylglycerol; DAG: diacylglycerol; Glc: glucose; GroP: glycerol-phosphate; anchor- LLD: gentiobiosyl-diacylglycerol. Figure adapted from Percy and Gründling, 2014 5. B. Scheme of flipping assay. NBD-Anchor-LLD lipids (red spheres) are irreversibly reduced (black spheres) by dithionite (dit.). In protein-free liposomes only outer-leaflet fluorophores are reduced. In proteoliposomes containing LtaA (yellow boxes), a larger portion of the fluorophores are reduced due to exchange. Full fluorescence quenching will be achieved after prolonged incubation (dashed arrow). C. Flipping of NBD-Anchor-LLD by LtaA. Representative traces shown are from protein-free liposomes, proteoliposomes containing either LtaA or a functionally unrelated transporter (bacterial choline transporter) (n ≥ 3). Asterisk marks addition of dithionite. Source data for C are available with the paper online.