Nordahl Emma Andersson, Rydengård Victoria, Mörgelin Matthias, Schmidtchen Artur
Section of Dermatology and Venereology, Department of Clinical Sciences, Lund, Biomedical Center, Lund University, Tornavägen 10, SE-221 84 Lund, Sweden.
J Biol Chem. 2005 Oct 14;280(41):34832-9. doi: 10.1074/jbc.M507249200. Epub 2005 Aug 9.
Antimicrobial peptides are important effectors of the innate immune system. These peptides belong to a multifunctional group of molecules that apart from their antibacterial activities also interact with mammalian cells and glycosaminoglycans and control chemotaxis, apoptosis, and angiogenesis. Here we demonstrate a novel antimicrobial activity of the heparin-binding and cell-binding domain 5 of high molecular weight kininogen. Antimicrobial epitopes of domain 5 were characterized by analysis of overlapping peptides. A peptide, HKH20 (His(479)-His(498)), efficiently killed the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and the Gram-positive Enterococcus faecalis. Fluorescence microscopy and electron microscopy demonstrated that HKH20 binds to and induces breaks in bacterial membranes. Furthermore, no discernible hemolysis or membrane-permeabilizing effects on eukaryotic cells were noted. Proteolytic degradation of high molecular weight kininogen by neutrophil-derived proteases as well as the metalloproteinase elastase from P. aeruginosa yielded fragments comprising HKH20 epitopes, indicating that kininogen-derived antibacterial peptides are released during proteolysis.
抗菌肽是天然免疫系统的重要效应分子。这些肽属于一类多功能分子，除了具有抗菌活性外，还能与哺乳动物细胞和糖胺聚糖相互作用，并控制趋化性、细胞凋亡和血管生成。在此，我们展示了高分子量激肽原的肝素结合和细胞结合结构域5的一种新型抗菌活性。通过对重叠肽段的分析来表征结构域5的抗菌表位。一种肽，HKH20（His(479)-His(498)），能有效杀死革兰氏阴性菌大肠杆菌和铜绿假单胞菌以及革兰氏阳性菌粪肠球菌。荧光显微镜和电子显微镜显示HKH20能结合并诱导细菌细胞膜破裂。此外，未观察到对真核细胞有明显的溶血或膜通透作用。中性粒细胞衍生的蛋白酶以及铜绿假单胞菌的金属蛋白酶弹性蛋白酶对高分子量激肽原的蛋白水解降解产生了包含HKH20表位的片段，这表明在蛋白水解过程中会释放出激肽原衍生的抗菌肽。
