Department of Biochemistry and Molecular Biology, Johns Hopkins School of Public Health, Baltimore, MD 21205, USA.
J Struct Biol. 2012 Dec;180(3):551-62. doi: 10.1016/j.jsb.2012.09.001. Epub 2012 Sep 13.
The autophagy-related proteins are thought to serve multiple functions in Plasmodium and are considered essential to parasite survival and development. We have studied two key interacting proteins, Atg8 and Atg3, of the autophagy pathway in Plasmodium falciparum. These proteins are vital for the formation and elongation of the autophagosome and essential to the process of macroautophagy. Autophagy may be required for conversion of the sporozoite into erythrocytic-infective merozoites and may be crucial for other functions during asexual blood stages. Here we describe the identification of an Atg8 family interacting motif (AIM) in Plasmodium Atg3, which binds Plasmodium Atg8. We determined the co-crystal structure of PfAtg8 with a short Atg3¹⁰³⁻¹¹⁰ peptide, corresponding to this motif, to 2.2 Å resolution. Our in vitro interaction studies are in agreement with our X-ray crystal structure. Furthermore they suggest an important role for a unique Apicomplexan loop absent from human Atg8 homologues. Prevention of the protein-protein interaction of full length PfAtg8 with PfAtg3 was achieved at low micromolar concentrations with a small molecule, 1,2,3-trihydroxybenzene. Together our structural and interaction studies represent a starting point for future antimalarial drug discovery and design for this novel protein-protein interaction.
自噬相关蛋白被认为在疟原虫中具有多种功能，被认为对寄生虫的生存和发育至关重要。我们研究了疟原虫自噬途径中的两个关键相互作用蛋白，Atg8 和 Atg3。这些蛋白质对于自噬体的形成和伸长至关重要，对于巨自噬过程也是必不可少的。自噬可能是将孢子转化为红细胞感染性裂殖子所必需的，并且在无性血阶段的其他功能中可能是至关重要的。在这里，我们描述了在疟原虫 Atg3 中鉴定出一种 Atg8 家族相互作用基序（AIM），该基序与疟原虫 Atg8 结合。我们确定了 PfAtg8 与短 Atg3¹⁰³⁻¹¹⁰ 肽的共晶体结构，对应于该基序，分辨率为 2.2 Å。我们的体外相互作用研究与 X 射线晶体结构一致。此外，它们表明一个独特的 Apicomplexan 环在人类 Atg8 同源物中缺失，对于这个相互作用具有重要作用。小分子 1,2,3-三羟基苯以低微摩尔浓度实现全长 PfAtg8 与 PfAtg3 的蛋白-蛋白相互作用的抑制。我们的结构和相互作用研究代表了针对这种新型蛋白-蛋白相互作用的未来抗疟药物发现和设计的起点。
