Heller W T, Waring A J, Lehrer R I, Harroun T A, Weiss T M, Yang L, Huang H W
Department of Physics, Rice University, Houston, Texas 77251, USA.
Biochemistry. 2000 Jan 11;39(1):139-45. doi: 10.1021/bi991892m.
Lipid bilayers containing the antimicrobial peptide protegrin-1 (PG-1) were studied by lamellar X-ray diffraction. Previously, we have shown that the peptide exists in two distinct states when associated with lipid bilayers depending on the peptide concentration [Heller, W. T., Waring, A. J., Lehrer, R. I., and Huang, H. W. (1998) Biochemistry 37, 17331-17338]. For concentrations below a lipid-dependent threshold, PG-1 exhibits a unique oriented circular dichroism spectrum called the S state. X-ray experiments show that in this state PG-1 decreases the thickness of the lipid bilayer in proportion to the peptide concentration, similar to alamethicin's membrane thinning effect. This indicates that the S state is adsorbed in the headgroup region of the lipid bilayer, where the peptide is in an inactive state. For PG-1 above the threshold concentration, X-ray diffraction shows that the interaction between the peptide and the bilayer changes significantly. These results suggest that PG-1 has the same concentration-gated mechanism of action as alamethicin.
通过层状X射线衍射研究了含有抗菌肽防御素-1（PG-1）的脂质双层。此前，我们已经表明，根据肽浓度，该肽与脂质双层结合时存在两种不同状态[海勒，W.T.，韦林，A.J.，莱勒，R.I.，和黄，H.W.（1998年）《生物化学》37卷，17331 - 17338页]。对于低于脂质依赖性阈值的浓度，PG-1呈现出一种独特的取向圆二色光谱，称为S态。X射线实验表明，在此状态下，PG-1会使脂质双层的厚度与肽浓度成比例地减小，这与短杆菌肽A的膜变薄效应类似。这表明S态吸附在脂质双层的头部区域，此时肽处于无活性状态。对于高于阈值浓度的PG-1，X射线衍射表明肽与双层之间的相互作用发生了显著变化。这些结果表明，PG-1与短杆菌肽A具有相同的浓度门控作用机制。
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