Picas Laura, Montero M Teresa, Morros Antoni, Vázquez-Ibar J L, Hernández-Borrell Jordi
Departament de Fisicoquímica, Facultat de Farmàcia, UB.
Biochim Biophys Acta. 2010 Feb;1798(2):291-6. doi: 10.1016/j.bbamem.2009.06.024. Epub 2009 Jul 10.
Biochemical and structural work has revealed the importance of phospholipids in biogenesis, folding and functional modulation of membrane proteins. Therefore, the nature of protein-phospholipid interaction is critical to understand such processes. Here, we have studied the interaction of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG) mixtures with the lactose permease (LacY), the sugar/H(+) symporter from Escherichia coli and a well characterized membrane transport protein. FRET measurements between single-W151/C154G LacY reconstituted in a lipid mixture composed of POPE and POPG at different molar ratios and pyrene-labeled PE or PG revealed a different phospholipid distribution between the annular region of LacY and the bulk lipid phase. Results also showed that both PE and PG can be part of the annular region, being PE the predominant when the PE:PG molar ratio mimics the membrane of E. coli. Furthermore, changes in the thermotropic behavior of phospholipids located in this annular region confirm that the interaction between LacY and PE is stronger than that of LacY and PG. Since PE is a proton donor, the results obtained here are discussed in the context of the transport mechanism of LacY.
生化和结构研究揭示了磷脂在膜蛋白生物合成、折叠及功能调节中的重要性。因此，蛋白质 - 磷脂相互作用的本质对于理解这些过程至关重要。在此，我们研究了1 - 棕榈酰 - 2 - 油酰 - sn - 甘油 - 3 - 磷酸乙醇胺（POPE）和1 - 棕榈酰 - 2 - 油酰 - sn - 甘油 - 3 - [磷酸 - rac -（1 - 甘油）]（POPG）混合物与乳糖通透酶（LacY）的相互作用，LacY是来自大肠杆菌的糖/H⁺同向转运蛋白，也是一种特征明确的膜转运蛋白。在以不同摩尔比由POPE和POPG组成的脂质混合物中重构的单W151/C154G LacY与芘标记的PE或PG之间进行荧光共振能量转移（FRET）测量，结果显示LacY的环形区域和本体脂质相之间的磷脂分布不同。结果还表明，PE和PG都可以是环形区域的一部分，当PE:PG摩尔比模拟大肠杆菌膜时，PE占主导地位。此外，位于该环形区域的磷脂热致行为的变化证实，LacY与PE的相互作用强于LacY与PG的相互作用。由于PE是质子供体，本文所得结果将在LacY转运机制的背景下进行讨论。
