Wang Geqing, Drinkwater Nyssa, Drew Damien R, MacRaild Christopher A, Chalmers David K, Mohanty Biswaranjan, Lim San Sui, Anders Robin F, Beeson James G, Thompson Philip E, McGowan Sheena, Simpson Jamie S, Norton Raymond S, Scanlon Martin J
Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Wellington Rd, Clayton, Victoria 3800, Australia.
J Mol Biol. 2016 Oct 9;428(20):3986-3998. doi: 10.1016/j.jmb.2016.07.001. Epub 2016 Jul 14.
The interaction between apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2) plays a key role in the invasion of red blood cells by Plasmodium parasites. Disruption of this critical protein-protein interaction represents a promising avenue for antimalarial drug discovery. In this work, we exploited a 13-residue β-hairpin based on the C-terminal loop of RON2 to probe a conserved binding site on Plasmodium falciparum AMA1. A series of mutations was synthetically engineered into β-hairpin peptides to establish structure-activity relationships. The best mutations improved the binding affinity of the β-hairpin peptide by ~7-fold for 3D7 AMA1 and ~14-fold for FVO AMA1. We determined the crystal structures of several β-hairpin peptides in complex with AMA1 in order to define the structural features and specific interactions that contribute to improved binding affinity. The same mutations in the longer RON2sp2 peptide (residues 2027-2055 of RON2) increased the binding affinity by >30-fold for 3D7 and FVO AMA1, producing K values of 2.1nM and 0.4nM, respectively. To our knowledge, this is the most potent strain-transcending peptide reported to date and represents a valuable tool to characterize the AMA1-RON2 interaction.
顶膜抗原1（AMA1）与棒状体颈部蛋白2（RON2）之间的相互作用在疟原虫入侵红细胞过程中起关键作用。破坏这种关键的蛋白质-蛋白质相互作用是抗疟药物研发的一个有前景的途径。在这项研究中，我们基于RON2的C末端环开发了一个13个残基的β-发夹结构，以探测恶性疟原虫AMA1上的一个保守结合位点。通过合成方式对β-发夹肽进行了一系列突变，以建立构效关系。最佳突变使β-发夹肽与3D7 AMA1的结合亲和力提高了约7倍，与FVO AMA1的结合亲和力提高了约14倍。我们测定了几种与AMA1形成复合物的β-发夹肽的晶体结构，以确定有助于提高结合亲和力的结构特征和特定相互作用。较长的RON2sp2肽（RON2的2027-2055位残基）中的相同突变使与3D7和FVO AMA1的结合亲和力提高了30倍以上，产生的K值分别为2.1nM和0.4nM。据我们所知，这是迄今为止报道的最有效的跨菌株肽，是表征AMA1-RON2相互作用的一个有价值的工具。
