The Receptor-Binding Domain in the VP1u Region of Parvovirus B19
The Receptor-Binding Domain in the VP1u Region of Parvovirus B19
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DOI：
10.3390/v8030061
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发表时间：
2016-03-01
期刊：
影响因子：
4.7
通讯作者：
Ros, Carlos
中科院分区：
文献类型：
--
作者：
Leisi, Remo;Di Tommaso, Chiarina;Ros, Carlos
细小病毒B19（Parvovirus B19，B19 V）是引起轻度儿童传染性红斑的人类病原体。B19 V显示骨髓中红系祖细胞的非常窄的组织向性，这是由高度限制的摄取决定的。我们先前已经表明，特异性内化是由病毒蛋白1独特区域（VP 1u）与一种未知细胞受体的相互作用介导的。为了定位VP 1u内的受体结合结构域（RBD），我们分析了截短和突变对重组蛋白进入UT 7/Epo细胞的内化能力的影响。在这里，我们报告说，VP 1u的N-末端氨基酸5-80是必要的和足够的细胞结合和内化;因此，这个N-末端区域代表B19 V摄取所需的RBD。使用定点突变，我们进一步确定了一组重要的氨基酸在VP 1u内化中发挥关键作用。计算机模拟预测和实验结果表明，RBD的结构是一个刚性折叠的三个α-螺旋。最后，我们发现VP 1u的二聚化导致了相当大的增强的细胞结合和内化。总之，我们确定了介导B19 V摄取的RBD，并在该序列中绘制了功能和结构基序。这些发现揭示了B19 V的摄取过程，这有助于了解感染的发病机制和免疫系统对病毒的中和作用。
Parvovirus B19 (B19V) is known as the human pathogen causing the mild childhood disease erythema infectiosum. B19V shows an extraordinary narrow tissue tropism for erythroid progenitor cells in the bone marrow, which is determined by a highly restricted uptake. We have previously shown that the specific internalization is mediated by the interaction of the viral protein 1 unique region (VP1u) with a yet unknown cellular receptor. To locate the receptor-binding domain (RBD) within the VP1u, we analyzed the effect of truncations and mutations on the internalization capacity of the recombinant protein into UT7/Epo cells. Here we report that the N-terminal amino acids 5-80 of the VP1u are necessary and sufficient for cellular binding and internalization; thus, this N-terminal region represents the RBD required for B19V uptake. Using site-directed mutagenesis, we further identified a cluster of important amino acids playing a critical role in VP1u internalization. In silico predictions and experimental results suggest that the RBD is structured as a rigid fold of three alpha-helices. Finally, we found that dimerization of the VP1u leads to a considerably enhanced cellular binding and internalization. Taken together, we identified the RBD that mediates B19V uptake and mapped functional and structural motifs within this sequence. The findings reveal insights into the uptake process of B19V, which contribute to understand the pathogenesis of the infection and the neutralization of the virus by the immune system.