Wang Lei, Bütikofer Peter
Institute of Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland.
Biology (Basel). 2023 Oct 25;12(11):1367. doi: 10.3390/biology12111367.
Lactose permease (LacY) from belongs to the major facilitator superfamily. It facilitates the co-transport of β-galactosides, including lactose, into cells by using a proton gradient towards the cell. We now show that LacY is capable of scrambling glycerophospholipids across a membrane. We found that purified LacY reconstituted into liposomes at various protein to lipid ratios catalyzed the rapid translocation of fluorescently labeled and radiolabeled glycerophospholipids across the proteoliposome membrane bilayer. The use of LacY mutant proteins unable to transport lactose revealed that glycerophospholipid scrambling was independent of H/lactose transport activity. Unexpectedly, in a LacY double mutant locked into an occluded conformation glycerophospholipid, scrambling activity was largely inhibited. The corresponding single mutants revealed the importance of amino acids G46 and G262 for glycerophospholipid scrambling of LacY.
来自[具体来源未提及]的乳糖通透酶（LacY）属于主要转运体超家族。它利用朝向细胞的质子梯度促进包括乳糖在内的β-半乳糖苷共转运进入细胞。我们现在表明，LacY能够使甘油磷脂跨膜翻转。我们发现，以各种蛋白质与脂质比例重构到脂质体中的纯化LacY催化荧光标记和放射性标记的甘油磷脂快速跨蛋白脂质体膜双层转运。使用无法转运乳糖的LacY突变蛋白表明，甘油磷脂翻转与H/乳糖转运活性无关。出乎意料的是，在锁定为封闭构象的LacY双突变体中，甘油磷脂翻转活性受到很大抑制。相应的单突变体揭示了氨基酸G46和G262对LacY甘油磷脂翻转的重要性。
