Molecular dissection of placental malaria protein VAR2CSA interaction with a chemo-enzymatically synthesized chondroitin sulfate library
Molecular dissection of placental malaria protein VAR2CSA interaction with a chemo-enzymatically synthesized chondroitin sulfate library
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DOI：
10.1007/s10719-016-9685-z
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发表时间：
2016-12-01
影响因子：
3
通讯作者：
Salanti, Ali
中科院分区：
文献类型：
--
作者：
Sugiura, Nobuo;Clausen, Thomas Mandel;Salanti, Ali
胎盘型疟疾是由恶性疟原虫引起的一种严重感染，其特征在于感染的红细胞（IE）在孕妇胎盘中的选择性积累。胎盘粘附由疟疾VAR 2CSA蛋白介导，其与存在于胎盘组织中的硫酸软骨素（CS）蛋白聚糖相互作用。CS是一种线性酸性多糖，由D-葡萄糖醛酸和N-乙酰基-D-半乳糖胺的重复二糖单元组成，这些二糖单元在不同位置被硫酸酯基团修饰。先前的报告表明，胎盘粘附IE与硫酸软骨素A（CSA）的异常低硫酸化形式相关，部分硫酸化十二糖是相互作用的最小基序。然而，这种CS链的精细分子结构仍不清楚。在这项研究中，我们的特点是CS链相互作用的重组最小CS-结合区的VAR 2CSA（rVAR 2）使用CS库的各种定义的长度和硫酸盐组合物。用细菌软骨素聚合酶和重组CS磺基转移酶化学-酶促合成CS文库。我们发现N-乙酰基-d-半乳糖胺残基的C-4硫酸化对于支持rVAR 2结合是至关重要的，而没有其他硫酸修饰显示出效果。rVAR 2与CS的相互作用与C-4硫酸化程度和CS链长高度相关。我们证实了与rVAR 2结合的最小结构是三硫酸化CSA十二糖，并发现高度硫酸化CSA二十糖是比十二糖更有效的rVAR 2结合抑制剂。这些结果表明，CSA衍生物可能作为针对胎盘疟疾的治疗策略的目标。
Placental malaria, a serious infection caused by the parasite Plasmodium falciparum, is characterized by the selective accumulation of infected erythrocytes (IEs) in the placentas of the pregnant women. Placental adherence is mediated by the malarial VAR2CSA protein, which interacts with chondroitin sulfate (CS) proteoglycans present in the placental tissue. CS is a linear acidic polysaccharide composed of repeating disaccharide units of d-glucuronic acid and N-acetyl-d-galactosamine that are modified by sulfate groups at different positions. Previous reports have shown that placental-adhering IEs were associated with an unusually low sulfated form of chondroitin sulfate A (CSA) and that a partially sulfated dodecasaccharide is the minimal motif for the interaction. However, the fine molecular structure of this CS chain remains unclear. In this study, we have characterized the CS chain that interacts with a recombinant minimal CS-binding region of VAR2CSA (rVAR2) using a CS library of various defined lengths and sulfate compositions. The CS library was chemo-enzymatically synthesized with bacterial chondroitin polymerase and recombinant CS sulfotransferases. We found that C-4 sulfation of the N-acetyl-d-galactosamine residue is critical for supporting rVAR2 binding, whereas no other sulfate modifications showed effects. Interaction of rVAR2 with CS is highly correlated with the degree of C-4 sulfation and CS chain length. We confirmed that the minimum structure binding to rVAR2 is a tri-sulfated CSA dodecasaccharide, and found that a highly sulfated CSA eicosasaccharide is a more potent inhibitor of rVAR2 binding than the dodecasaccharides. These results suggest that CSA derivatives may potentially serve as targets in therapeutic strategies against placental malaria.