Monitoring pyrene excimers in lactose permease liposomes: revealing the presence of phosphatidylglycerol in proximity to an integral membrane protein.
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.
Picas
Laura
L
Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain.
Merino-Montero
Sandra
S
Morros
Antoni
A
Hernández-Borrell
Jordi
J
Montero
M Teresa
MT
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
D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D008081:Liposomes; D009004:Monosaccharide Transport Proteins; D010715:Phosphatidylglycerols; D011721:Pyrenes; D027981:Symporters; D014364:Tryptophan