CHARACTERAZATION OF DBL DOMAIN PROTEINS IN P FALCIPARUM

许多特定的分子相互作用发生在 疟疾寄生虫及其宿主，包括细胞黏附、玫瑰花环和 红细胞的侵袭，是由寄生虫配体介导的，由 DBL结构域(Duffy结合样蛋白)超家族的蛋白质。DBL- 结构域是一个富含半胱氨酸的结构域，具有保守性和可变性 功能，并已被证明编码的配体 红细胞受体血糖素-A和达菲抗原。在 恶性疟原虫红细胞入侵过程可利用 至少涉及三种不同红细胞的几种不同途径 感受器。已知的唯一介导恶性疟原虫入侵的配体 其中一个途径是EBA-175，它是一种DBL结构域蛋白，与 血糖素-A这项建议中要检验的假设是 几个新发现的DBL结构域家族的蛋白质也具有功能 在入侵过程中作为红细胞受体的配体。这个 这些蛋白质的特性将涉及确定它们的 用荧光、电子和共聚焦定位寄生虫 显微镜观察和检测这些蛋白质结合的能力 红血球。对主持人身份的初步调查 这些配体的受体也将被传导，利用结合 异源系统中表达的区域，并分析它们的能力 结合酶修饰的红细胞，或基因修饰的红细胞 缺乏明确的表面分子。使用基因敲除的潜力 缺乏这些假定的红细胞结合基因的寄生虫 蛋白质也将被研究。内部的多态程度 编码在入侵中起作用的蛋白质的基因将是 研究表明这些蛋白质是否可能适应免疫 压力或受体的异质性。最后，内部的保留要素 红细胞结合蛋白的DBL结构域将被开发 以确定该基因家族的其他成员，这些成员也可能是 参与了入侵。

Many of the specific molecular interactions that occur between the malarial parasite and its host, including cytoadherence, rosetting, and erythrocyte invasion, are mediated by parasite ligands encoded by proteins of the DBL-domain (Duffy binding like) superfamily. The DBL- domain is a cysteine rich domain with both conserved and variable features, and has been demonstrated to encode the ligand for the erythrocyte receptors glycophorin-A and the Duffy antigen. In the process of erythrocyte invasion P. falciparum is capable of utilizing several distinct pathways involving at least three different erythrocyte receptors. The only P. falciparum ligand known to mediate invasion by one of these pathways is EBA-175, a DBL-domain protein that binds to glycophorin-A. The hypothesis to be tested in this proposal is that several newly identified proteins of the DBL-domain family also function as ligands for erythrocyte receptors during invasion. The characterization of these proteins will involve determining their location within the parasite by fluorescence, electron and confocal microscopy and testing the ability of these proteins to bind erythrocytes. Preliminary investigation of the identity of the host receptor for these ligands will also be conducted, utilizing the binding regions expressed in a heterologous system, and assaying their ability to bind enzymatically modified erythrocytes, or those genetically deficient in defined surface molecules. The potential of using knockout parasites lacking the genes for these putative erythrocyte binding proteins will also be investigated. The extent to polymorphism within the genes encoding proteins shown to play a role in invasion will be investigated to suggest whether these proteins may be adapting to immune pressure or receptor heterogeneity. Finally, conserved features within the DBL-domains of the erythrocyte binding proteins will be exploited to identify additional members of this gene family which may also be involved in invasion.