title: Monitoring pyrene excimers in lactose permease liposomes: revealing the presence of phosphatidylglycerol in proximity to an integral membrane protein.
abstract: In this study, we examined the annular lipid composition of the transmembrane protein lactose permease (LacY) from Escherichia coli. LacY was reconstituted into 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphoethanolamine (POPE) and 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-3-[Phospho-rac-(1-glycerol)] (POPG) and labeled with 1-hexadecanoyl-2-(1-pyrenedecanoyl)-sn-Glycero-3-phosphoglycerol (PPDPG) at a 3:0.99:0.01 molar ratio. Pyrene excimer formation was monitored by exciting a single tryptophan mutant of the protein (T320W). The results suggest that POPG remains segregated in the vicinity of the protein, most likely forming part of the annular composition. The possible involvement of POPG in hydrogen binding with the protein, as well as the molecular mechanism of LacY, is also discussed in the context of the proteomic network theory.
authors.affiliation: Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Picas
authors.forename: Sandra
authors.initials: S
authors.lastname: Merino-Montero
authors.forename: Antoni
authors.initials: A
authors.lastname: Morros
authors.forename: Jordi
authors.initials: J
authors.lastname: Hernández-Borrell
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Montero
mesh_terms: D019943:Amino Acid Substitution; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D006860:Hydrogen Bonding; D008081:Liposomes; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D009004:Monosaccharide Transport Proteins / Q000737:chemistry* / Q000235:genetics; D010715:Phosphatidylglycerols / Q000737:chemistry; D011721:Pyrenes / Q000737:chemistry; D013053:Spectrophotometry; D027981:Symporters / Q000737:chemistry* / Q000235:genetics; D013816:Thermodynamics; D014364:Tryptophan / Q000737:chemistry / Q000235:genetics
chemical_list: D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D008081:Liposomes; D009004:Monosaccharide Transport Proteins; D010715:Phosphatidylglycerols; D011721:Pyrenes; D027981:Symporters; D014364:Tryptophan