Broadly neutralizing antibody PGT121 allosterically modulates CD4 binding via recognition of the HIV-1 gp120 V3 base and multiple surrounding glycans.
Broadly neutralizing antibody PGT121 allosterically modulates CD4 binding via recognition of the HIV-1 gp120 V3 base and multiple surrounding glycans.
复制标题
DOI：
10.1371/journal.ppat.1003342
复制
发表时间：
2013
期刊：
影响因子：
6.7
通讯作者：
Wilson IA
中科院分区：
文献类型：
--
作者：
Julien JP;Sok D;Khayat R;Lee JH;Doores KJ;Walker LM;Ramos A;Diwanji DC;Pejchal R;Cupo A;Katpally U;Depetris RS;Stanfield RL;McBride R;Marozsan AJ;Paulson JC;Sanders RW;Moore JP;Burton DR;Poignard P;Ward AB;Wilson IA
最近发现了新的广泛且强效的中和HIV - 1抗体，它们在很大程度上依赖于gp120的N332聚糖来识别Env。从一名非洲捐赠者体内分离出的PGT121抗体家族成员，能够中和约70%的循环分离株，其中位半数抑制浓度（IC50）小于0.05微克/毫升。在此，我们表明该家族的三个成员PGT121、PGT122和PGT123具有非常相似的晶体结构。一个由24个残基组成的长互补决定区3（HCDR3）将抗体结合位点分为两个功能表面，一个是由重链互补决定区（CDRs）形成的开放面，另一个是由轻链互补决定区1（LCDR1）、轻链互补决定区3（LCDR3）和HCDR3末端形成的细长面。对抗体互补位进行丙氨酸扫描诱变显示，细长面上的残基在中和过程中起着关键作用，而在PGT121结构中容纳复杂双触角聚糖的开放面似乎起着次要作用。对一种工程重组Env gp140三聚体（SOSIP.664）进行的负染电子显微镜重建显示，与先前已被描述且同样依赖N332聚糖的抗体PGT128相比，PGT122以更垂直于刺突顶面的角度与gp120外域相互作用。然后我们利用等温滴定量热法（ITC）和荧光激活细胞分选术（FACS）证明，尽管PGT121抗体的表位远离CD4结合位点，但它们能抑制CD4与gp120的结合。综合这些结构、功能和生物物理结果表明，PGT121抗体可能通过一种变构机制干扰Env与受体的结合，在这种机制中，关键结构元件，如V3基部、N332寡甘露糖聚糖以及周围的聚糖，包括一种假定的V1/V2复合双触角聚糖，在构象上受到限制。
据估计，目前约有3300万成人和儿童感染人类免疫缺陷病毒1型（HIV - 1），全球患病率为0.8%。在缺乏治愈方法的情况下，研发一种保护性疫苗是控制这一全球性流行病长期追求的目标。HIV - 1 Env是唯一的病毒表面糖蛋白，它介导病毒与宿主细胞的结合和进入，这是病毒生命周期的第一步。最近，大量令人兴奋的新抗体被发现，它们与HIV - 1 Env相互作用并抑制靶细胞的感染（即中和病毒）。在此，我们从结构上对一种重组HIV - 1 Env与一类此类抗体，即PGT121家族抗体的相互作用进行了表征。这些研究揭示了一种新的HIV - 1 Env识别模式。通过与HIV - 1 Env膜远端顶端附近的关键结构元件相互作用，这些抗体能够干扰与CD4的结合，CD4是T细胞上HIV - 1感染所必需的受体。这些观察结果进一步描绘了HIV - 1 Env上一个依赖聚糖的易损位点，可用于疫苗设计工作。
New broad and potent neutralizing HIV-1 antibodies have recently been described that are largely dependent on the gp120 N332 glycan for Env recognition. Members of the PGT121 family of antibodies, isolated from an African donor, neutralize ∼70% of circulating isolates with a median IC50 less than 0.05 µg ml−1. Here, we show that three family members, PGT121, PGT122 and PGT123, have very similar crystal structures. A long 24-residue HCDR3 divides the antibody binding site into two functional surfaces, consisting of an open face, formed by the heavy chain CDRs, and an elongated face, formed by LCDR1, LCDR3 and the tip of the HCDR3. Alanine scanning mutagenesis of the antibody paratope reveals a crucial role in neutralization for residues on the elongated face, whereas the open face, which accommodates a complex biantennary glycan in the PGT121 structure, appears to play a more secondary role. Negative-stain EM reconstructions of an engineered recombinant Env gp140 trimer (SOSIP.664) reveal that PGT122 interacts with the gp120 outer domain at a more vertical angle with respect to the top surface of the spike than the previously characterized antibody PGT128, which is also dependent on the N332 glycan. We then used ITC and FACS to demonstrate that the PGT121 antibodies inhibit CD4 binding to gp120 despite the epitope being distal from the CD4 binding site. Together, these structural, functional and biophysical results suggest that the PGT121 antibodies may interfere with Env receptor engagement by an allosteric mechanism in which key structural elements, such as the V3 base, the N332 oligomannose glycan and surrounding glycans, including a putative V1/V2 complex biantennary glycan, are conformationally constrained. An estimated 33 million adults and children currently live with the human immunodeficiency virus type 1 (HIV-1), which represents a global prevalence of 0.8%. In the absence of a cure, the development of a protective vaccine is the long sought-after goal in containment of the pandemic. HIV-1 Env is the sole viral surface glycoprotein and mediates viral engagement and entry into host cells, which constitutes the first step of the virus life cycle. Recently, a plethora of exciting new antibodies have been discovered that interact with HIV-1 Env and inhibit infection of target cells (i.e. neutralize the virus). Here, we structurally characterize the interaction of a recombinant HIV-1 Env with one class of such antibodies, namely antibodies of the PGT121 family. These studies have uncovered a novel mode of HIV-1 Env recognition. By interacting with key structural elements of HIV-1 Env near the apex at its membrane-distal end, these antibodies can interfere with binding to CD4, the receptor on T cells that is required for HIV-1 infection. These observations further delineate a glycan-dependent site of vulnerability on HIV-1 Env that can be used in vaccine design efforts.
登录
查看更多内容
影响因子：
64.8
作者：
Huang J;Ofek G;Laub L;Louder MK;Doria-Rose NA;Longo NS;Imamichi H;Bailer RT;Chakrabarti B;Sharma SK;Alam SM;Wang T;Yang Y;Zhang B;Migueles SA;Wyatt R;Haynes BF;Kwong PD;Mascola JR;Connors M
通讯作者：
Connors M
影响因子：
4.4
作者：
Go, Eden P.;Chang, Qing;Liao, Hua-Xin;Sutherland, Laura L.;Alam, S. Munir;Haynes, Barton F.;Desaire, Heather
通讯作者：
Desaire, Heather
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
3
作者：
Hohn, Michael;Tang, Grant;Ludtke, Steven J.
通讯作者：
Ludtke, Steven J.
DOI：
10.1107/s0907444909052925
发表时间：
2010-02
期刊：
Acta crystallographica. Section D, Biological crystallography
影响因子：
--
作者：
Adams PD;Afonine PV;Bunkóczi G;Chen VB;Davis IW;Echols N;Headd JJ;Hung LW;Kapral GJ;Grosse-Kunstleve RW;McCoy AJ;Moriarty NW;Oeffner R;Read RJ;Richardson DC;Richardson JS;Terwilliger TC;Zwart PH
通讯作者：
Zwart PH