Crystal Structure of PG16 and Chimeric Dissection with Somatically Related PG9: Structure-Function Analysis of Two Quaternary-Specific Antibodies That Effectively Neutralize HIV-1
Crystal Structure of PG16 and Chimeric Dissection with Somatically Related PG9: Structure-Function Analysis of Two Quaternary-Specific Antibodies That Effectively Neutralize HIV-1
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DOI：
10.1128/jvi.00966-10
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发表时间：
2010-08-15
影响因子：
5.4
通讯作者：
Kwong, Peter D.
中科院分区：
文献类型：
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作者：
Pancera, Marie;McLellan, Jason S.;Kwong, Peter D.
HIV-1抵抗大多数抗体的中和。然而，两种体细胞相关的人类抗体，PG9和PG16，各自中和70%至80%的循环HIV-1分离株。在这里，我们分别在2.4埃和4.0埃的单斜晶格和正交晶格中展示了PG16抗原结合片段的结构，并结合结构分析、paratope解剖和中和评估来确定三个不寻常的PG9/PG16特征的功能相关性：n-连锁糖基化、广泛的亲和力成熟和重链- 3互补决定区（CDR H3），这是在人类抗体中观察到的最长的区域之一。糖基化延伸到轻链可变结构域的一侧，并且不需要中和。CDR H3形成了一个斧头状的子结构域，占CDR表面的42%，斧头状的结构域比其他组合环高出约20埃。通过对轻链、重链和CDR H3的PG9和PG16的嵌合交换的综合分析，揭示了结构-功能关系。嵌合交换通常在功能上互补，PG9/PG16中和的差异主要与CDR H3的残基差异有关。与此同时，基因组V基因嵌合还原表现出分离依赖效应，亲和成熟在增加中和广度（P = 0.036）和效力（P < 0.0001）方面发挥了显著作用。特异的CDR H3和广泛的亲和力成熟的结构和功能细节提供了对广泛中和抗体如PG9和PG16的中和机制和激发途径的见解。
HIV-1 resists neutralization by most antibodies. Two somatically related human antibodies, PG9 and PG16, however, each neutralize 70 to 80% of circulating HIV-1 isolates. Here we present the structure of the antigen-binding fragment of PG16 in monoclinic and orthorhombic lattices at 2.4 and 4.0 angstrom, respectively, and use a combination of structural analysis, paratope dissection, and neutralization assessment to determine the functional relevance of three unusual PG9/PG16 features: N-linked glycosylation, extensive affinity maturation, and a heavy chain-third complementarity-determining region (CDR H3) that is one of the longest observed in human antibodies. Glycosylation extended off the side of the light chain variable domain and was not required for neutralization. The CDR H3 formed an axe-shaped subdomain, which comprised 42% of the CDR surface, with the axe head looming similar to 20 angstrom above the other combining loops. Comprehensive sets of chimeric swaps between PG9 and PG16 of light chain, heavy chain, and CDR H3 were employed to decipher structure-function relationships. Chimeric swaps generally complemented functionally, with differences in PG9/PG16 neutralization related primarily to residue differences in CDR H3. Meanwhile, chimeric reversions to genomic V genes showed isolate-dependent effects, with affinity maturation playing a significant role in augmenting neutralization breadth (P = 0.036) and potency (P < 0.0001). The structural and functional details of extraordinary CDR H3 and extensive affinity maturation provide insights into the neutralization mechanism of and the elicitation pathway for broadly neutralizing antibodies like PG9 and PG16.