Shebek Kevin, Schantz Allen B, Sines Ian, Lauser Kathleen, Velegol Stephanie, Kumar Manish
†Department of Chemical Engineering and ‡Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Langmuir. 2015 Apr 21;31(15):4496-502. doi: 10.1021/acs.langmuir.5b00015. Epub 2015 Apr 10.
A cationic protein isolated from the seeds of the Moringa oleifera tree has been extensively studied for use in water treatment in developing countries and has been proposed for use in antimicrobial and therapeutic applications. However, the molecular basis for the antimicrobial action of this peptide, Moringa oleifera cationic protein (MOCP), has not been previously elucidated. We demonstrate here that a dominant mechanism of MOCP antimicrobial activity is membrane fusion. We used a combination of cryogenic electron microscopy (cryo-EM) and fluorescence assays to observe and study the kinetics of fusion of membranes in liposomes representing model microbial cells. We also conducted cryo-EM experiments on E. coli cells where MOCP was seen to fuse the inner and outer membranes. Coarse-grained molecular dynamics simulations of membrane vesicles with MOCP molecules were used to elucidate steps in peptide adsorption, stalk formation, and fusion between membranes.
从辣木树种子中分离出的一种阳离子蛋白已被广泛研究用于发展中国家的水处理，并被提议用于抗菌和治疗应用。然而，这种肽——辣木阳离子蛋白（MOCP）的抗菌作用的分子基础此前尚未阐明。我们在此证明，MOCP抗菌活性的主要机制是膜融合。我们结合低温电子显微镜（cryo-EM）和荧光测定法，观察和研究了代表模型微生物细胞的脂质体中膜融合的动力学。我们还对大肠杆菌细胞进行了cryo-EM实验，发现MOCP能使内膜和外膜融合。使用含有MOCP分子的膜囊泡的粗粒度分子动力学模拟来阐明肽吸附、柄形成和膜间融合的步骤。
