Conserved residues in the Plasmodium vivax Duffy-binding protein ligand domain are critical for erythrocyte receptor recognition
Conserved residues in the Plasmodium vivax Duffy-binding protein ligand domain are critical for erythrocyte receptor recognition
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DOI：
10.1073/pnas.0405421101
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发表时间：
2004-11-02
影响因子：
11.1
通讯作者：
Adams, JH
中科院分区：
文献类型：
--
作者：
VanBuskirk, KM;Sevova, E;Adams, JH
疟原虫裂殖子侵入人红细胞依赖于疟原虫配体对红细胞表面特异性受体的识别。间日疟原虫裂殖子的侵入完全依赖于疟原虫配体Duffy结合蛋白（DBP）对Duffy血型抗原的识别。间日疟原虫的受体识别依赖于DBP胞外部分IN末端的富含半胱氨酸的结构域，即DBL结构域或区域II。与受体识别有关的DBP的最小区域位于DBL结构域的半胱氨酸4和8之间，这是寄生虫分离株中等位基因多态性率最高的区域。我们以前发现，在这个区域的等位基因多态性改变了间日疟原虫DBL结构域的抗原特性，这与受体特异性的变化归因于恶性疟原虫的一些同源配体的多态性形成对比。为了进一步研究保守和多态性残基的相对重要性，在这个DBL中心区域，我们确定了受体识别的位点定向诱变的关键残基。77个表面预测的残基的Sal-1 DBL结构域被丙氨酸取代，并通过瞬时转染COS细胞表面上的突变蛋白的表达测定红细胞结合活性。丙氨酸取代的功能效应从零到DBL红细胞结合活性的完全丧失不等。导致配体功能丧失的突变大多发生在保守残基的不连续簇中，而几乎所有多态性残基的突变都不影响红细胞结合。这些数据描绘DBL结构域残基的受体识别所必需的。
Malaria merozoite invasion of human erythrocytes depends on recognition of specific erythrocyte surface receptors by parasite ligands. Plasmodium, vivax merozoite invasion is totally dependent on the recognition of the Duffy blood group antigen by the parasite ligand Duffy-binding protein (DBP). Receptor recognition by A vivax relies on a cysteine-rich domain, the DBL domain or region II, at the IN terminus of the extracellular portion of DBP. The minimal region of the DBP implicated for receptor recognition lies between cysteines 4 and 8 of the DBL domain, which is a region that also has the highest rate of allelic polymorphisms among parasite isolates. We previously found that allelic polymorphisms in this region altered the A vivax DBL domain antigenic character, which contrasts with changes in receptor specificity attributed to polymorphisms in some homologous ligands of Plasmodium falciparum. To further investigate the relative importance of conserved and polymorphic residues within this DBL central region, we identified residues critical for receptor recognition by site-directed mutagenesis. Seventy-seven surface-predicted residues of the Sal-1 DBL domain were substituted with alanine and assayed for erythrocyte binding activity by expression of the mutant proteins on the surface of transiently transfected COS cells. The functional effect of alanine substitution varied from nil to complete loss of DBL erythrocyte-binding activity. Mutations that caused loss of ligand function mostly occurred in discontinuous clusters of conserved residues, whereas nearly all mutations in polymorphic residues did not affect erythrocyte binding. These data delineate DBL domain residues essential for receptor recognition.