Using fluorous amino acids to probe the effects of changing hydrophobicity on the physical and biological properties of the β-hairpin antimicrobial peptide protegrin-1
Using fluorous amino acids to probe the effects of changing hydrophobicity on the physical and biological properties of the β-hairpin antimicrobial peptide protegrin-1
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DOI：
10.1021/bi801045n
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发表时间：
2008-09-02
期刊：
影响因子：
2.9
通讯作者：
Marsh, E. Neil G.
中科院分区：
文献类型：
--
作者：
Gottler, Lindsey M.;Bea, Roberto de la Salud;Marsh, E. Neil G.
前列环素是β-发夹形成类抗菌肽的有力成员。它们的抗菌活性的关键是它们在与细菌膜结合时组装成低聚结构。为了研究多肽的物理化学性质与其生物活性之间的关系，我们合成了Protigin-1的变种，其中疏水核心的关键残基valine-14和-16被改变为亮氨酸和广泛氟化的类似物六氟亮氨酸。这些取代具有使多肽逐渐变得更疏水性的效果，同时对二级结构的扰动最小。含有亮氨酸的多肽对几种常见致病菌的活性明显高于野生型，而六氟亮氨酸取代的多肽对几种细菌的活性显著降低。等温滴定量热法测量显示，与模拟细菌膜脂组成的小单膜囊泡结合的多肽的相互作用发生了显着变化。野生型和亮氨酸取代的前列环素的结合等温线表明，膜-肽相互作用以静电作用为主，而六氟亮氨酸取代的前列环素的等温线表明结合的静电成分减少。值得注意的是，这两种取代似乎都改变了脂-肽相互作用的化学计量比，表明这些取代可能稳定寡聚化形式的前列环素，这些寡聚形式被认为是β-桶状膜孔结构组装的中间产物。
Protegrins are potent members of the beta-hairpin-forming class of antimicrobial peptides. Key to their antimicrobial activity is their assembly into oligomeric structures upon binding to the bacterial membrane. To examine the relationship between the physicochemical properties of the peptide and its biological activity, we have synthesized variants of protegrin-1 in which key residues in the hydrophobic core, valine-14 and -16, are changed to leucine and to the extensively fluorinated analogue hexafluoroleucine. These substitutions have the effect of making the peptide progressively more hydrophobic while minimally perturbing the secondary structure. The leucine-containing peptide was significantly more active than wild-type protegrin against several common pathogenic bacterial strains, whereas the hexafluoroleucine-substituted peptide, in contrast, showed significantly diminished activity against several bacterial strains. Isothermal titration calorimetry measurements revealed significant changes in the interaction of the peptides binding to small unilamelar vesicles that mimic the lipid composition of the bacterial membrane. The binding isotherms for wild-type and leucine-substituted protegrins indicate that electrostatic interactions dominate the membrane-peptide interaction, whereas the isotherm for the hexafluoroleucine-substituted protegrin suggests a diminished electrostatic component to binding. Notably both of these substitutions appear to alter the stoichiometry of the lipid-peptide interaction, suggesting that these substitutions may stabilize oligomerized forms of protegrin that are postulated to be intermediates in the assembly of the beta-barrel membrane pore structure.