Structural changes in the model of the outer cell membrane of Gram-negative bacteria interacting with melittin: an in situ spectroelectrochemical study
Structural changes in the model of the outer cell membrane of Gram-negative bacteria interacting with melittin: an in situ spectroelectrochemical study
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DOI：
10.1039/d0fd00039f
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发表时间：
2021-12-24
影响因子：
3.4
通讯作者：
Khairalla, Bishoy
中科院分区：
文献类型：
--
作者：
Brand, Izabella;Khairalla, Bishoy
革兰氏阴性菌的细胞膜与抗菌肽相互作用呈现复杂的超分子组装。制造细菌细胞膜模型仍然是一个巨大的实验挑战。Langmuir-Blodgett和Langmuir-Schaefer （LS-LB）转移使得多组分不对称脂质双分子层沉积在金表面成为可能。用两种脂质：1-棕榈酰-2-油酰-森-甘油-3-磷酸乙醇胺（POPE）和二[3-脱氧-d-甘露-辛基松脂]-脂质A （KLA）在Au（111）底物上沉积革兰氏阴性菌外膜模型。使用金作为固体衬底可以控制膜电位。本文讨论了生理电场作用下模型膜与蜂毒素抗菌肽相互作用的分子尺度变化。外膜与蜂毒素的相互作用导致膜电容和对离子和水的渗透性增加。结合蜂毒素的外膜的稳定性在正膜电位下下降。利用原位偏振调制红外反射吸收光谱研究了与蜂毒蛋白相互作用的外膜结构的膜电位依赖性变化。与蜂毒素的相互作用不影响酯羰基的水合作用。然而，在与蜂毒蛋白相互作用后，KLA中羧酸基的取向和氢键网络发生了巨大的变化。我们认为肽c端氨基酸中的正电荷基团与KLA的极性头基直接相互作用。同时，结合蜂窝蜂素的膜中烃类链的排列顺序增加。脂质链和横跨膜的肽之间的疏水匹配似乎是双分子层碳氢链区域排序的原因。n端进入膜的疏水区，形成通往亲水性头基团的通道。
The cell membrane of Gram-negative bacteria interacting with an antimicrobial peptide presents a complex supramolecular assembly. Fabrication of models of bacterial cell membranes remains a large experimental challenge. Langmuir-Blodgett and Langmuir-Schaefer (LS-LB) transfer makes possible the deposition of multicomponent asymmetric lipid bilayers onto a gold surface. Two lipids: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and di[3-deoxy-d-manno-octulosonyl]-lipid A (KLA) were used to deposit a model of the outer membrane of Gram-negative bacteria on the Au(111) substrate. The use of gold as the solid substrate enables control of the membrane potential. Molecular scale changes in the model membrane exposed to physiological electric fields and interacting with melittin antimicrobial peptide are discussed in this paper. The interaction of the outer membrane with melittin leads to an increase in the membrane capacitance and permeability to ions and water. The stability of the outer membrane with bound melittin decreases at positive membrane potentials. In situ polarization modulation infrared reflection absorption spectroscopy is used to investigate membrane potential-dependent changes in the structure of the outer membrane interacting with melittin. The hydration of the ester carbonyl groups is not affected by the interaction with melittin. However, the orientation and hydrogen bond network with the carboxylate groups in KLA changes drastically after POPE-KLA bilayer interacts with melittin. We propose that the positively charged groups in the amino acids present at the C-terminus of the peptide interact directly with the polar head group of KLA. Simultaneously, the packing order in hydrocarbon chains in the membrane with bound melittin increases. A hydrophobic match between the chains in the lipids and the peptide, which spans the membrane, seems to be responsible for the ordering of the hydrocarbon chains region of the bilayer. The N-terminus enters into the hydrophobic region of the membrane and forms a channel to the hydrophilic head groups in POPE.