Verardi Raffaello, Traaseth Nathaniel J, Shi Lei, Porcelli Fernando, Monfregola Luca, De Luca Stefania, Amodeo Pietro, Veglia Gianluigi, Scaloni Andrea
Departments of Chemistry and Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
Biochim Biophys Acta. 2011 Jan;1808(1):34-40. doi: 10.1016/j.bbamem.2010.08.008. Epub 2010 Aug 16.
Distinctin is a 47-residue antimicrobial peptide, which interacts with negatively charged membranes and is active against Gram-positive and Gram-negative bacteria. Its primary sequence comprises two linear chains of 22 (chain 1) and 25 (chain 2) residues, linked by a disulfide bridge between Cys19 of chain 1 and Cys23 of chain 2. Unlike other antimicrobial peptides, distinctin in the absence of the lipid membrane has a well-defined three-dimensional structure, which protects it from protease degradation. Here, we used static solid-state NMR spectroscopy in mechanically aligned lipid bilayers (charged or zwitterionic) to study the topology of distinctin in lipid bilayers. We found that this heterodimeric peptide adopts an ordered conformation absorbed on the surface of the membrane, with the long helix (chain 2), approximately parallel to the lipid bilayer (~5° from the membrane plane) and the short helix (chain 1) forming a ~24° angle with respect to the bilayer plane. Since the peptide does not disrupt the macroscopic alignment of charged or zwitterionic lipid bilayers at lipid-to-protein molar ratio of 50:1, it is possible that higher peptide concentrations might be needed for pore formation, or alternatively, distinctin elicits its cell disruption action by another mechanism.
Distinctin是一种由47个氨基酸残基组成的抗菌肽，它能与带负电荷的膜相互作用，对革兰氏阳性菌和革兰氏阴性菌均有活性。其一级序列由两条线性链组成，一条含22个残基（链1），另一条含25个残基（链2），通过链1的Cys19与链2的Cys23之间的二硫键相连。与其他抗菌肽不同，在没有脂质膜的情况下，Distinctin具有明确的三维结构，这使其免受蛋白酶降解。在这里，我们使用机械排列的脂质双层（带电荷或两性离子）中的静态固态核磁共振光谱来研究Distinctin在脂质双层中的拓扑结构。我们发现，这种异二聚体肽在膜表面采取有序构象，长螺旋（链2）大致平行于脂质双层（与膜平面约呈5°角），短螺旋（链1）相对于双层平面形成约24°角。由于在脂质与蛋白质摩尔比为50:1时，该肽不会破坏带电荷或两性离子脂质双层的宏观排列，因此可能需要更高的肽浓度来形成孔，或者Distinctin通过另一种机制引发其细胞破坏作用。
