Marshall V M, Tieqiao W, Coppel R L
The Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Mol Biochem Parasitol. 1998 Jul 1;94(1):13-25. doi: 10.1016/s0166-6851(98)00045-0.
We have analysed a 10.5 kb region of chromosome 2 in Plasmodium falciparum that encompasses the coding region of four genes. Three genes are arranged in a head-to-tail orientation and encode the merozoite surface proteins MSP2 and MSP4 as well as a previously unreported sequence that encodes a polypeptide with the characteristics of a merozoite surface protein, now designated MSP5. The fourth gene, asl, is arranged in a tail-to-tail orientation with msp2 and has homology with prokaryotic and eukaryotic genes encoding adenylosuccinate lyase (ASL), an enzyme involved in purine biosynthesis and salvage. The genes, arranged in the order msp4, msp5, msp2 and asl, are separated by intergenic distances of 1021, 1017 and 722 bp, respectively. msp4 and msp5 are clearly related genes, each being composed of 2 exons and encoding proteins of identical length. Both msp4 and msp5 encode proteins that contain hydrophobic signal sequences, apparent glycosylphosphatidylinositol (GPI) attachment signals and a single epidermal growth factor-like (EGF-like) domain at their carboxyl termini. Nevertheless, the remainder of their protein coding regions are quite dissimilar. It appears that one of these genes arose as a result of a relatively ancient gene duplication event and both genes have subsequently diverged considerably. This study shows that msp5 is transcribed in asexual stages and its encoded product is a 40 kDa protein that appears to be located on the merozoite surface as determined by immunofluorescence assays.
我们分析了恶性疟原虫2号染色体上一个10.5 kb的区域，该区域包含四个基因的编码区。其中三个基因呈头对头排列，编码裂殖子表面蛋白MSP2和MSP4，以及一个先前未报道的序列，该序列编码一种具有裂殖子表面蛋白特征的多肽，现命名为MSP5。第四个基因asl与msp2呈尾对尾排列，与编码腺苷酸琥珀酸裂解酶（ASL）的原核和真核基因具有同源性，ASL是一种参与嘌呤生物合成和补救的酶。这些基因按msp4、msp5、msp2和asl的顺序排列，基因间隔分别为1021、1017和722 bp。msp4和msp5显然是相关基因，每个基因都由2个外显子组成，编码长度相同的蛋白质。msp4和msp5都编码含有疏水信号序列、明显的糖基磷脂酰肌醇（GPI）附着信号以及在其羧基末端有一个单一表皮生长因子样（EGF样）结构域的蛋白质。然而，它们蛋白质编码区的其余部分却大不相同。似乎这些基因中的一个是相对古老的基因复制事件的结果，并且两个基因随后都发生了相当大的分化。这项研究表明，msp5在无性阶段转录，其编码产物是一种40 kDa的蛋白质，通过免疫荧光测定法确定该蛋白质似乎位于裂殖子表面。
