Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 2012 Nov 20;109(47):E3268-77. doi: 10.1073/pnas.1217207109. Epub 2012 Oct 30.
Broadly neutralizing HIV antibodies (bNAbs) can recognize carbohydrate-dependent epitopes on gp120. In contrast to previously characterized glycan-dependent bNAbs that recognize high-mannose N-glycans, PGT121 binds complex-type N-glycans in glycan microarrays. We isolated the B-cell clone encoding PGT121, which segregates into PGT121-like and 10-1074-like groups distinguished by sequence, binding affinity, carbohydrate recognition, and neutralizing activity. Group 10-1074 exhibits remarkable potency and breadth but no detectable binding to protein-free glycans. Crystal structures of unliganded PGT121, 10-1074, and their likely germ-line precursor reveal that differential carbohydrate recognition maps to a cleft between complementarity determining region (CDR)H2 and CDRH3. This cleft was occupied by a complex-type N-glycan in a "liganded" PGT121 structure. Swapping glycan contact residues between PGT121 and 10-1074 confirmed their importance for neutralization. Although PGT121 binds complex-type N-glycans, PGT121 recognized high-mannose-only HIV envelopes in isolation and on virions. As HIV envelopes exhibit varying proportions of high-mannose- and complex-type N-glycans, these results suggest promiscuous carbohydrate interactions, an advantageous adaptation ensuring neutralization of all viruses within a given strain.
广谱中和 HIV 抗体 (bNAbs) 可以识别 gp120 上依赖于碳水化合物的表位。与先前表征的识别高甘露糖 N-糖的依赖于聚糖的 bNAbs 不同，PGT121 在聚糖微阵列中结合复杂型 N-聚糖。我们分离了编码 PGT121 的 B 细胞克隆，该克隆分为 PGT121 样和 10-1074 样群，其特征在于序列、结合亲和力、碳水化合物识别和中和活性。10-1074 组表现出显著的效力和广度，但对无蛋白聚糖没有可检测的结合。未配体结合的 PGT121、10-1074 及其可能的种系前体的晶体结构表明，差异碳水化合物识别映射到互补决定区 (CDR)H2 和 CDRH3 之间的裂隙。该裂隙在配体结合的 PGT121 结构中被一个复杂型 N-聚糖占据。在 PGT121 和 10-1074 之间交换聚糖接触残基证实了它们对中和的重要性。尽管 PGT121 结合复杂型 N-聚糖，但 PGT121 可单独识别高甘露糖型 HIV 包膜，也可识别病毒粒子上的高甘露糖型 HIV 包膜。由于 HIV 包膜表现出不同比例的高甘露糖型和复杂型 N-聚糖，这些结果表明存在混杂的碳水化合物相互作用，这是一种有利的适应，可确保对给定株系内的所有病毒进行中和。
