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，包括细胞粘附、玫瑰花结和 红细胞侵袭是由寄生虫配体介导的 DBL 结构域（Duffy 结合样）超家族的蛋白质。 DBL- 结构域是富含半胱氨酸的结构域，具有保守性和可变性 特征，并已被证明可以编码配体 红细胞受体血型糖蛋白-A 和达菲抗原。 在 恶性疟原虫的红细胞侵袭过程能够利用 几个不同的途径涉及至少三种不同的红细胞 受体。 已知唯一介导恶性疟原虫侵袭的配体 这些途径之一是 EBA-175，一种 DBL 结构域蛋白，可结合 血型糖蛋白-A。 本提案要检验的假设是 DBL 结构域家族的几种新发现的蛋白质也发挥作用 作为入侵过程中红细胞受体的配体。 的 这些蛋白质的表征将涉及确定它们的 通过荧光、电子和共聚焦在寄生虫内定位 显微镜检查并测试这些蛋白质的结合能力 红细胞。 初步调查主人身份 这些配体的受体也将进行，利用结合 在异源系统中表达的区域，并测定它们的能力 结合酶促修饰的红细胞，或那些经过基因改造的红细胞 缺乏确定的表面分子。 使用淘汰赛的潜力 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。 内多态性的程度 编码在入侵中发挥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 压力或受体异质性。 最后，内部保留的特征 红细胞结合蛋白的 DBL 结构域将被利用 以确定该基因家族的其他成员，这些成员也可能是 参与入侵。

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.