Structural and functional characterization of protein–lipid interactions of the Salmonella typhimurium melibiose transporter MelB

• DOI: 10.1186/s12915-018-0553-0
• Publication Date: 2018-08-03T09:04:03Z
• Authors: Parameswaran Hari...; Elena Tikhonova; João Medeiros-Silva; Aike Jeucken; Mikhail V. Bogdanov; William Dowhan; Jos F. Brouwers; Markus Weingarth; Lan Guan
• Keywords: Phosphatidylethanolamine; Phosphatidylglycerol

Membrane lipids play critical roles in the structure and function of membrane-embedded transporters. Salmonella typhimurium MelB (MelBSt) is a symporter coupling melibiose translocation with cation (Na+, Li+, or H+). We present an extensive study on effects specific phospholipids MelBSt transport catalyzed by this protein.Lipidomic analysis thin-layer chromatography (TLC) experiments reveal that at least one phosphatidylethanolamine (PE) phosphatidylglycerol (PG) molecule associate high affinities. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy confirmed presence lipid tails glycerol backbones co-purified MelBSt; headgroups PG were also observed. Studies lipid-engineered strains, including PE-deficient, cardiolipin (CL)- PG-deficient, CL-deficient show lack PE PG, however not CL, largely inhibits both H+- Na+-coupled active to different extents. Interestingly, neither co-substrate binding (melibiose Na+) nor folding stability are affected changing compositions. Remarkably, delipidated only 2-3 bound lipids, regardless headgroup species, exhibits unchanged melting temperature values as shown circular dichroism spectroscopy.(1) Lipid interacting may contribute MelBSt. (2) The but important transport; however, do modulate