Giraldo L E, Grab D J, Wiser M F
Department of Tropical Medicine, Tulane University School of Public Health, New Orleans, Louisiana 70112, USA.
J Eukaryot Microbiol. 1998 Sep-Oct;45(5):528-34. doi: 10.1111/j.1550-7408.1998.tb05112.x.
The malarial parasite dramatically affects the structure and function of the erythrocyte membrane by exporting proteins that specifically interact with the host membrane. This report describes the complete sequence and some biochemical properties of a 93-kDa Plasmodium chabaudi chabaudi protein that interacts with the host erythrocyte membrane. Approximately 40% of the deduced protein sequence consists of tandem repeats of 14 amino acids that are rich in glutamic acid residues. Comparison of the repeat sequences from two different P. c. chabaudi strains derived from the same initial isolate revealed an exact duplication of 294 nucleotides suggesting a recent unequal crossing-over event. However, in spite of this potentially high level of intragenic recombination activity, the repeat sequences from P. c. adami are rather conserved suggesting structural or functional constraints on the protein and tandem repeats. The 93-kDa protein exists in an oligomeric form as revealed by gel filtration chromatography and non-denaturing gel electrophoresis. A predominantly alpha-helical predicted secondary structure and a discrepancy between the estimated molecular sizes determined from non-denaturing gel electrophoresis and gel filtration chromatography suggest that the protein is a long rod-shaped or fibrillar, protein. Attributes shared between the 93-kDa protein, some P. falciparum proteins with glutamate-rich tandem repeats, and cytoskeletal proteins suggest that these parasite proteins function as cytoskeletal proteins that possibly stabilize the erythrocyte membrane.
疟原虫通过输出与宿主膜特异性相互作用的蛋白质，极大地影响红细胞膜的结构和功能。本报告描述了一种与宿主红细胞膜相互作用的93 kDa沙氏疟原虫蛋白的完整序列和一些生化特性。推导的蛋白质序列中约40%由富含谷氨酸残基的14个氨基酸的串联重复序列组成。对来自同一初始分离株的两种不同沙氏疟原虫菌株的重复序列进行比较，发现294个核苷酸的精确重复，表明最近发生了不等交换事件。然而，尽管这种基因内重组活性可能很高，但来自亚当斯沙氏疟原虫的重复序列相当保守，表明该蛋白质和串联重复序列存在结构或功能限制。凝胶过滤色谱和非变性凝胶电泳显示，93 kDa蛋白以寡聚体形式存在。预测的主要为α螺旋二级结构，以及非变性凝胶电泳和凝胶过滤色谱测定的估计分子大小之间的差异表明，该蛋白质是一种长杆状或纤维状蛋白质。93 kDa蛋白、一些具有富含谷氨酸串联重复序列的恶性疟原虫蛋白和细胞骨架蛋白之间共有的特性表明，这些寄生虫蛋白起着细胞骨架蛋白的作用，可能稳定红细胞膜。
