Lipid binding attenuates channel closure of the outer membrane protein OmpF.
Lipid binding attenuates channel closure of the outer membrane protein OmpF.
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DOI：
10.1073/pnas.1721152115
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发表时间：
2018-06-26
影响因子：
11.1
通讯作者：
Robinson CV
中科院分区：
文献类型：
--
作者：
Liko I;Degiacomi MT;Lee S;Newport TD;Gault J;Reading E;Hopper JTS;Housden NG;White P;Colledge M;Sula A;Wallace BA;Kleanthous C;Stansfeld PJ;Bayley H;Benesch JLP;Allison TM;Robinson CV
外膜孔蛋白通常被认为是小分子穿过脂质双层的被动通道。使用本机质谱实验，我们确定了pH敏感的脂质结合机制的外膜孔蛋白F，这使得增加的大肠杆菌素衍生的肽通过开放通道的线程。分子动力学模拟和通道记录实验的支持下，我们认为，这种机制衰减通道开放响应于环境条件的变化，特别是pH值。这些研究结果具有重要的后果质谱实验，其中电荷的作用往往被忽视，他们也可以帮助提供了解抗生素，获得通过孔蛋白介导的途径进入革兰氏阴性菌。脂质和蛋白质之间的强相互作用主要通过带电荷的头基和氨基酸侧链的缔合发生，使得两个伙伴的质子化状态重要。在这里，我们使用本地质谱探索作为外膜孔蛋白F（OmpF）的电荷的函数的脂质结合。我们发现，结合的阴离子磷脂酰甘油（POPG）或两性离子磷脂酰胆碱（POPC）OmpF是敏感的电喷雾极性，而电荷的影响是不太明显的其他蛋白质在外部或线粒体膜：ferripyoverdine受体（FpvA）或电压依赖性阴离子通道（VDAC）。只有边际电荷诱导的差异观察内膜蛋白：氨通道（AmtB）或机械敏感通道。为了理解这些不同的敏感性，我们进行了广泛的生物信息学分析的膜蛋白结构，发现OmpF，并在较小程度上FpvA和VDAC，具有高密度的碱性和酸性残基在其脂质头基结合区域的局部。粗粒度的分子动力学模拟，在混合的脂质双层，进一步牵连电荷的变化，通过证明优先结合的阴离子POPG的两性离子POPC质子化的OmpF，没有观察到相同程度的AmtB的效果。此外，电生理学和质谱为基础的配体结合实验，在低pH值，表明POPG可以保持开放构象的OmpF通道延长的时间。由于外膜几乎完全由阴离子脂多糖组成，具有与POPG相似的头基性质，这种阴离子脂质结合可以防止OmpF通道的关闭，从而增加使用孔蛋白介导的途径的抗生素的进入。
Outer-membrane porins are often considered as passive conduits of small molecules across lipid bilayers. Using native mass spectrometry experiments we identify a pH-sensitive lipid-binding mechanism of outer membrane porin F, which enables increased threading of a colicin-derived peptide through open channels. Supported by molecular dynamics simulations and channel recording experiments, we posit that this mechanism attenuates channel opening in response to changes in environmental conditions, specifically pH. These findings have important consequences for mass spectrometry experiments, wherein the role of charge is often overlooked, and they also could help provide understanding of antibiotics that gain access to Gram-negative bacteria through porin-mediated pathways. Strong interactions between lipids and proteins occur primarily through association of charged headgroups and amino acid side chains, rendering the protonation status of both partners important. Here we use native mass spectrometry to explore lipid binding as a function of charge of the outer membrane porin F (OmpF). We find that binding of anionic phosphatidylglycerol (POPG) or zwitterionic phosphatidylcholine (POPC) to OmpF is sensitive to electrospray polarity while the effects of charge are less pronounced for other proteins in outer or mitochondrial membranes: the ferripyoverdine receptor (FpvA) or the voltage-dependent anion channel (VDAC). Only marginal charge-induced differences were observed for inner membrane proteins: the ammonia channel (AmtB) or the mechanosensitive channel. To understand these different sensitivities, we performed an extensive bioinformatics analysis of membrane protein structures and found that OmpF, and to a lesser extent FpvA and VDAC, have atypically high local densities of basic and acidic residues in their lipid headgroup-binding regions. Coarse-grained molecular dynamics simulations, in mixed lipid bilayers, further implicate changes in charge by demonstrating preferential binding of anionic POPG over zwitterionic POPC to protonated OmpF, an effect not observed to the same extent for AmtB. Moreover, electrophysiology and mass-spectrometry–based ligand-binding experiments, at low pH, show that POPG can maintain OmpF channels in open conformations for extended time periods. Since the outer membrane is composed almost entirely of anionic lipopolysaccharide, with similar headgroup properties to POPG, such anionic lipid binding could prevent closure of OmpF channels, thereby increasing access of antibiotics that use porin-mediated pathways.
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影响因子：
64.8
作者：
Glenwright AJ;Pothula KR;Bhamidimarri SP;Chorev DS;Baslé A;Firbank SJ;Zheng H;Robinson CV;Winterhalter M;Kleinekathöfer U;Bolam DN;van den Berg B
通讯作者：
van den Berg B
DOI：
10.1016/j.bbapap.2008.11.005
发表时间：
2009-05
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Delcour AH
通讯作者：
Delcour AH
影响因子：
4.8
作者：
Hakizimana, Pierre;Masureel, Matthieu;Govaerts, Cedric
通讯作者：
Govaerts, Cedric
影响因子：
3.4
作者：
Baslé, A;Iyer, R;Delcour, AH
通讯作者：
Delcour, AH
影响因子：
7.4
作者：
Hogan, Christopher J., Jr.;Carroll, James A.;Rohrs, Henry W.;Biswas, Pratim;Gross, Michael L.
通讯作者：
Gross, Michael L.