Identification of a CD36-related thrombospondin 1-binding domain in HIV-1 envelope glycoprotein gp120: Relationship to HIV-1-specific inhibitory factors in human saliva
Identification of a CD36-related thrombospondin 1-binding domain in HIV-1 envelope glycoprotein gp120: Relationship to HIV-1-specific inhibitory factors in human saliva
复制标题
DOI：
10.1084/jem.187.1.25
复制
发表时间：
1998-01-05
影响因子：
15.3
通讯作者：
Laurence, J
中科院分区：
文献类型：
--
作者：
Crombie, R;Silverstein, RL;Laurence, J
人类和非人类灵长类动物的唾液在体外和体内均能延缓 HIV-1 的感染性。由于血小板反应蛋白 1 (TSP1) 是一种高分子量三聚体糖蛋白，浓缩在唾液中，可以在体外抑制多种病原体的感染性，因此我们试图确定 TSP1 在抑制 HIV 感染性中的作用。序列分析揭示了先前为细胞粘附受体CD36基因家族定义的TSP1识别基序，该基序位于HIV包膜糖蛋白gp120的V3环的二硫键连接的半胱氨酸残基的保守区域中，对于HIV与其高亲和力细胞受体CD4的结合非常重要。使用固相体外结合测定，我们证明了放射性标记的 TSP1 与固定化重组 gp120 的直接结合。基于肽阻断实验，TSP1-gp120 相互作用涉及 TSP1 的 1 型备解素样重复中的 CSVTCG 序列，TSP1 是已知的 CD36 结合位点。 TSP1 和源自 CD36 相关 TSP1 结合域的融合蛋白能够与放射性标记的可溶性 CD4 竞争与固定化 gp120 的结合。同时，纯化的 TSP1 抑制外周血单核细胞以及转化的 T 细胞和早单核细胞系的 HIV-1 感染。病毒聚集和直接阻断 HIV-1 感染所需的 TSP1 水平是生理性的，唾液 TSP1 的亲和力耗尽消除了全唾液对 HIV 感染性的 70% 以上的抑制作用。 TSP1-gp120 结合特异性的表征表明了一种直接阻断 HIV 感染性的机制，可用于阻止通过粘膜途径发生的 HIV 传播。
Human and non-human primate salivas retard the infectivity of HIV-1 in vitro and in vivo. Because thrombospondin 1 (TSP1), a high molecular weight trimeric glycoprotein, is concentrated in saliva and can inhibit the infectivity of diverse pathogens in vitro, we sought to determine the role of TSP1 in suppression of HIV infectivity. Sequence analysis revealed a TSP1 recognition motif previously defined for the CD36 gene family of cell adhesion receptors, in conserved regions nanking the disulfide-linked cysteine residues of the V3 loop of HIV envelope glycoprotein gp120, important for HIV binding to its high affinity cellular receptor CD4. Using solid-phase in vitro binding assays, we demonstrate direct binding of radiolabeled TSP1 to immobilized recombinant gp120. Based on peptide blocking experiments, the TSP1-gp120 interaction involves CSVTCG sequences in the type 1 properdin-like repeats of TSP1, the known binding site for CD36. TSP1 and fusion proteins derived fi-om CD36-related TSP1-binding domains were able to compete with radiolabeled soluble CD4 binding to immobilized gp120. In parallel, purified TSP1 inhibited HIV-1 infection of peripheral blood mononuclear cells and transformed T and promonocytic cell lines. Levels of TSP1 required for both viral aggregation and direct blockade of HIV-1 infection were physiologic, and affinity depletion of salivary TSP1 abrogated >70% of the inhibitory effect of whole saliva on HIV infectivity. Characterization of TSP1-gp120 binding specificity suggests a mechanism for direct blockade of HIV infectivity that might be exploited to retard HIV transmission that occurs via mucosal routes.