Antibody 17b binding at the coreceptor site weakens the kinetics of the interaction of envelope glycoprotein gp120 with CD4.
Antibody 17b binding at the coreceptor site weakens the kinetics of the interaction of envelope glycoprotein gp120 with CD4.
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抗体 17b 在辅助受体位点的结合削弱了包膜糖蛋白 gp120 与 CD4 相互作用的动力学。
DOI：
10.1021/bi001397m
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发表时间：
2001
期刊：
影响因子：
2.9
通讯作者：
Chaiken,I
中科院分区：
文献类型：
--
作者：
Zhang,W;Godillot,AP;Wyatt,R;Sodroski,J;Chaiken,I
HIV-1利用CD 4和趋化因子辅助受体进行病毒进入。gp 120上的辅助受体CCR 5结合位点与HIV-1的中和抗体17 b的结合表位部分重叠。我们设计了一种多组分生物传感器测定，以调查gp 120和它的受体之间的相互作用的动力学机制和协同效应的CCR 5结合位点上的CD 4结合位点，使用17 b作为替代的CCR 5。本研究检测了来自四个病毒株（JRFL、YU 2、89.6和HXB 2）及其相应的C1-、V1/V2-、C5-缺失突变体（ΔJRFL、Δ YU 2、Δ89.6和Δ HXB 2）的Env gp 120蛋白。我们发现，在原代和实验室适应的病毒株中，17 b通过降低结合速率和增加解离速率降低了所有四种全长Env gp 120对sCD 4的亲和力。17 b对全长gp 120与sCD 4结合的影响与sCD 4对gp 120 − 17 b相互作用的增强作用形成对比。对于相应的Env gp 120环缺失突变体，在17 b存在的情况下，gp 120 − sCD 4相互作用的解离速率大大降低，导致更高的亲和力（除了Δ HXB 2）。结果表明，当17 b是prebind全长gp 120，V1/V2环可能会重新定位到一个位置，部分阻断的CD 4结合位点，导致削弱的CD 4相互作用。考虑到17 b结合表位与CCR 5的结合位点部分重叠，动力学结果表明辅助受体CCR 5结合可能通过增加后者的解离速率对gp 120 − CD 4相互作用产生类似的“释放”效应。结果还表明，17 b的中和作用可能不仅来自于部分阻断CCR 5结合位点，而且还来自于降低gp 120的CD 4结合亲和力。17 b的这种负协同作用可能为设计病毒进入的拮抗剂提供了方法。
HIV-1 utilizes CD4 and the chemokine coreceptor for viral entry. The coreceptor CCR5 binding site on gp120 partially overlaps with the binding epitope of 17b, a neutralizing antibody of HIV-1. We designed a multicomponent biosensor assay to investigate the kinetic mechanism of interaction between gp120 and its receptors and the cooperative effect of the CCR5 binding site on the CD4 binding site, using 17b as a surrogate of CCR5. The Env gp120 proteins from four viral strains (JRFL, YU2, 89.6, and HXB2) and their corresponding C1-, V1/V2-, C5-deleted mutants (ΔJRFL, ΔYU2, Δ89.6, and ΔHXB2) were tested in this study. We found that, across the primary and lab-adapted virus strains, 17b reduced the affinity of all four full-length Env gp120s for sCD4 by decreasing the on-rate and increasing the off-rate. This effect of 17b on full-length gp120 binding to sCD4 contrasts with the enhancing effect of sCD4 on gp120−17b interaction. For the corresponding loop-deleted mutants of Env gp120, the off-rates of the gp120−sCD4 interaction were greatly reduced in the presence of 17b, resulting in higher affinities (except for that of ΔHXB2). The results suggest that, when 17b is prebound to full-length gp120, the V1/V2 loops may be relocated to a position that partially blocks the CD4-binding site, leading to weakening of the CD4 interaction. Given the fact that the 17b binding epitope partially overlaps with the binding site of CCR5, the kinetic results suggest that coreceptor CCR5 binding could have a similar “release” effect on the gp120−CD4 interaction by increasing the off-rate of the latter. The results also suggest that the neutralizing effect of 17b may arise not only from partially blocking the CCR5 binding site but also from reducing the CD4 binding affinity of gp120. This negative cooperative effect of 17b may provide insight into approaches to designing antagonists for viral entry.