Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
Department of Biochemistry, Nottingham Trent University, Nottingham, United Kingdom.
mBio. 2020 Sep 8;11(5):e01566-20. doi: 10.1128/mBio.01566-20.
RH5 is a secreted parasite ligand that is essential for erythrocyte invasion through direct interaction with the host erythrocyte receptor basigin. RH5 forms a tripartite complex with two other secreted parasite proteins, CyRPA and RIPR, and is tethered to the surface of the parasite through membrane-anchored P113. Antibodies against RH5, CyRPA, and RIPR can inhibit parasite invasion, suggesting that vaccines containing these three components have the potential to prevent blood-stage malaria. To further explore the role of the P113-RH5 interaction, we selected monoclonal antibodies against P113 that were either inhibitory or noninhibitory for RH5 binding. Using a Fab fragment as a crystallization chaperone, we determined the crystal structure of the RH5 binding region of P113 and showed that it is composed of two domains with structural similarities to rhamnose-binding lectins. We identified the RH5 binding site on P113 by using a combination of hydrogen-deuterium exchange mass spectrometry and site-directed mutagenesis. We found that a monoclonal antibody to P113 that bound to this interface and inhibited the RH5-P113 interaction did not inhibit parasite blood-stage growth. These findings provide further structural information on the protein interactions of RH5 and will be helpful in guiding the development of blood-stage malaria vaccines that target RH5. Malaria is a deadly infectious disease primarily caused by the parasite It remains a major global health problem, and there is no highly effective vaccine. A parasite protein called RH5 is centrally involved in the invasion of host red blood cells, making it-and the other parasite proteins it interacts with-promising vaccine targets. We recently identified a protein called P113 that binds RH5, suggesting that it anchors RH5 to the parasite surface. In this paper, we use structural biology to locate and characterize the RH5 binding region on P113. These findings will be important to guide the development of new antimalarial vaccines to ultimately prevent this disease, which affects some of the poorest people on the planet.
RH5 是一种分泌型寄生虫配体，通过与宿主红细胞受体 basigin 的直接相互作用，对红细胞入侵至关重要。RH5 与另外两种分泌型寄生虫蛋白 CyRPA 和 RIPR 形成三聚体复合物，并通过膜锚定的 P113 连接到寄生虫表面。针对 RH5、CyRPA 和 RIPR 的抗体可以抑制寄生虫入侵，这表明含有这三种成分的疫苗有可能预防血期疟疾。为了进一步探讨 P113-RH5 相互作用的作用，我们选择了针对 P113 的单克隆抗体，这些抗体对 RH5 结合具有抑制或非抑制作用。我们使用 Fab 片段作为结晶伴侣，确定了 P113 的 RH5 结合区域的晶体结构，并表明它由两个结构与鼠李糖结合凝集素相似的结构域组成。我们通过氢氘交换质谱和定点突变组合确定了 P113 上的 RH5 结合位点。我们发现，与该界面结合并抑制 RH5-P113 相互作用的针对 P113 的单克隆抗体不会抑制寄生虫血期生长。这些发现为 RH5 的蛋白质相互作用提供了进一步的结构信息，并将有助于指导针对 RH5 的血期疟疾疫苗的开发。疟疾是一种致命的传染病，主要由寄生虫引起。它仍然是一个主要的全球健康问题，而且没有非常有效的疫苗。一种叫做 RH5 的寄生虫蛋白在入侵宿主红细胞中起着核心作用，使其与它相互作用的其他寄生虫蛋白成为有希望的疫苗靶点。我们最近发现了一种叫做 P113 的蛋白质，它与 RH5 结合，表明它将 RH5 锚定在寄生虫表面。在本文中，我们使用结构生物学来定位和描述 P113 上的 RH5 结合区域。这些发现对于指导新的抗疟疾疫苗的开发将是重要的，最终将预防这种影响地球上一些最贫困人口的疾病。
