Department of Chemistry, Kings College London, Britannia House, 7 Trinity Street, London, SE1 1DB, UK.
Sci Rep. 2017 Oct 12;7(1):13056. doi: 10.1038/s41598-017-13290-7.
Lipids play key roles in Biology. Mechanical properties of the lipid bilayer influence their neighbouring membrane proteins, however it is unknown whether different membrane protein properties have the same dependence on membrane mechanics, or whether mechanics are tuned to specific protein processes of the protein. We study the influence of lipid lateral pressure and electrostatic effects on the in vitro reconstitution, folding, stability and function of a representative of the ubiquitous major facilitator transporter superfamily, lactose permease. Increasing the outward chain lateral pressure in the bilayer, through addition of lamellar phosphatidylethanolamine lipids, lowers lactose permease folding and reconstitution yields but stabilises the folded state. The presence of phosphatidylethanolamine is however required for correct folding and function. An increase in headgroup negative charge through the addition of phosphatidylglycerol lipids favours protein reconstitution but is detrimental to topology and function. Overall the in vitro folding, reconstitution, topology, stability and function of lactose permease are found to have different dependences on bilayer composition. A regime of lipid composition is found where all properties are favoured, even if suboptimal. This lays ground rules for rational control of membrane proteins in nanotechnology and synthetic biology by manipulating global bilayer properties to tune membrane protein behaviour.
脂质在生物学中起着关键作用。脂质双层的力学性质影响其邻近的膜蛋白，然而，目前尚不清楚不同的膜蛋白性质是否对膜力学有相同的依赖性，或者力学是否针对蛋白质的特定蛋白质过程进行了调整。我们研究了脂质横向压力和静电效应对体外重组、折叠、稳定性和功能的影响无处不在的主要易化转运蛋白超家族的代表，乳糖渗透酶。通过添加层状磷脂酰乙醇胺脂质，增加双层向外链的横向压力，降低乳糖渗透酶的折叠和重组产率，但稳定折叠状态。然而，磷脂酰乙醇胺的存在对于正确的折叠和功能是必需的。通过添加磷脂酰甘油脂质增加头基负电荷有利于蛋白质的重组，但对拓扑结构和功能不利。总的来说，乳糖渗透酶的体外折叠、重组、拓扑结构、稳定性和功能对双层组成有不同的依赖性。发现存在一种脂质组成的范围，所有性质都受到青睐，即使不是最优的。这为通过操纵全局双层性质来调整膜蛋白行为，在纳米技术和合成生物学中对膜蛋白进行合理控制奠定了基础。
