Rayner Julian C, Huber Curtis S, Galinski Mary R, Barnwell John W
Division of Parasitic Diseases, Centers for Disease Control and Prevention, National Center for Infectious Diseases, Atlanta, GA 30341, USA.
Mol Biochem Parasitol. 2004 Feb;133(2):287-96. doi: 10.1016/j.molbiopara.2003.10.017.
Malarial merozoites use an array of ligands, including members of the Reticulocyte Binding Like (RBL) super-family of invasion proteins, to identify and invade erythrocytes. RBL family members are large Type I membrane anchored proteins expressed at the invasive end of merozoites that share homology with the Reticulocyte Binding Proteins 1 and 2 (PvRBP1 and 2) of Plasmodium vivax. Plasmodium species vary widely both in the number and sequence of their RBL genes, with the recently completed Plasmodium falciparum genome containing five RBL genes. Of these, three encode proteins shown to be involved in erythrocyte invasion, a fourth is a pseudogene, and the role of the fifth is as yet unclear. In order to identify sequence similarities and differences that may have functional implications for erythrocyte invasion as well as to gain insights into the recent evolutionary history of the P. falciparum RBL genes, we have sequenced all five corresponding RBL genes from the chimpanzee parasite Plasmodium reichenowi, which is the closest phylogenetic relative of P. falciparum, yet is unable to invade human erythrocytes. Two of the five P. falciparum RBL genes have highly conserved complete open reading frames in both species, while the other three genes show evidence of gene conversion and rapid evolution. The RBL super-family, therefore, appears to be surprisingly dynamic and divergent, implying that it is involved in species-specific aspects of erythrocyte recognition and invasion.
疟原虫裂殖子利用一系列配体，包括入侵蛋白网织红细胞结合样（RBL）超家族的成员，来识别和侵入红细胞。RBL家族成员是大型I型膜锚定蛋白，在裂殖子的侵入端表达，与间日疟原虫的网织红细胞结合蛋白1和2（PvRBP1和2）具有同源性。疟原虫物种的RBL基因数量和序列差异很大，最近完成的恶性疟原虫基因组包含五个RBL基因。其中，三个编码的蛋白质已显示参与红细胞入侵，第四个是假基因，第五个的作用尚不清楚。为了确定可能对红细胞入侵具有功能影响的序列异同，并深入了解恶性疟原虫RBL基因的近期进化史，我们对来自黑猩猩疟原虫——莱氏疟原虫（Plasmodium reichenowi）的所有五个相应RBL基因进行了测序。莱氏疟原虫是恶性疟原虫最近的系统发育近亲，但无法侵入人类红细胞。五个恶性疟原虫RBL基因中的两个在这两个物种中具有高度保守的完整开放阅读框，而其他三个基因则显示出基因转换和快速进化的证据。因此，RBL超家族似乎具有惊人的动态性和差异性，这意味着它参与了红细胞识别和入侵的物种特异性方面。
