Aldolase provides an unusual binding site for thrombospondin-related anonymous protein in the invasion machinery of the malaria parasite
Aldolase provides an unusual binding site for thrombospondin-related anonymous protein in the invasion machinery of the malaria parasite
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DOI：
10.1073/pnas.0605301104
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发表时间：
2007-04-24
影响因子：
11.1
通讯作者：
Hol, Wim G. J.
中科院分区：
文献类型：
--
作者：
Bosch, Juergen;Buscaglia, Carlos A.;Hol, Wim G. J.
位于质膜下方的肌动球蛋白马达驱动顶复门寄生虫的运动和宿主细胞的侵袭，例如疟疾的病原体——恶性疟原虫和间日疟原虫。醛缩酶将运动肌动蛋白丝与血小板反应蛋白相关匿名蛋白 (TRAP) 家族的跨膜粘附蛋白连接起来，并在寄生虫表面传导运动力。 TRAP-醛缩酶相互作用是疟原虫子孢子入侵宿主肝细胞的一个独特且关键的特征，可能类似的相互作用对于裂殖子入侵红细胞至关重要。在这里，我们描述了恶性疟原虫醛缩酶 (PfAldo) 的 2.4 埃和 2.7 埃结构，该结构是从在伯氏疟原虫 TRAP 的 C 端六肽存在下生长的晶体中获得的。 TRAP 关键的倒数第二个色氨酸残基的吲哚环紧密贴合新形成的疏水口袋，该口袋仅由亲水残基界定：两个精氨酸、一个谷氨酸和一个谷氨酰胺。与未配体的 PfAldo 结构的比较表明，两个精氨酸采用新的侧链旋转异构体，而形成螺旋-环-螺旋单元的 25 个残基子结构域在结合 TRAP-尾部时发生变化。结构数据与诱导的 TRAP 结合袋中及其附近的 PfAldo 残基诱变后 TRAP 结合减少一致。值得注意的是，PfAldo 的 TRAP 和肌动蛋白结合位点似乎重叠，这表明醛缩酶活性位点区域的可塑性和酶的多聚体性质对于其在疟原虫入侵机制中有趣的非酶功能至关重要。
An actomyosin motor located underneath the plasma membrane drives motility and host-cell invasion of apicomplexan parasites such as Plasmodium faiciparum and Plasmodium vivax, the causative agents of malaria. Aldolase connects the motor actin filaments to transmembrane adhesive proteins of the thrombospondin-related anonymous protein (TRAP) family and transduces the motor force across the parasite surface. The TRAP-aldolase interaction is a distinctive and critical trait of host hepatocyte invasion by Plasmodium sporozoites, with a likely similar interaction crucial for erythrocyte invasion by merozoites. Here,we describe 2.4-angstrom and 2.7-angstrom structures of P. falciparum aldolase (PfAldo) obtained from crystals grown in the presence of the C-terminal hexapeptide of TRAP from Plasmodium berghei. The indole ring of the critical penultimate Trp-residue of TRAP fits snugly into a newly formed hydrophobic pocket, which is exclusively delimited by hydrophilic residues: two arginines, one glutamate, and one glutamine. Comparison with the unliganded PfAldo structure shows that the two arginines adopt new side-chain rotamers, whereas a 25-residue subdomain, forming a helix-loop-helix unit, shifts upon binding the TRAP-tail. The structural data are in agreement with decreased TRAP binding after mutagenesis of PfAldo residues in and near the induced TRAP-binding pocket. Remarkably, the TRAP- and actin-binding sites of PfAldo seem to overlap, suggesting that both the plasticity of the aldolase active-site region and the multimeric nature of the enzyme are crucial for its intriguing nonenzymatic function in the invasion machinery of the malaria parasite.