Cocrystal Structures of Antibody N60-i3 and Antibody JR4 in Complex with gp120 Define More Cluster A Epitopes Involved in Effective Antibody-Dependent Effector Function against HIV-1

Gohain, Neelakshi; Tolbert, W.D.; Acharya, Priyamvada; Yu, Long-Chuan; Liu, Tongyun; Zhao, Pingsen; Orlandi, Chiara; Visciano, Maria Luisa; Kamin-Lewis, Roberta; Sajadi, Mohammad M.; Martin, Loı̈c; Robinson, James E.; Kwong, Peter D.; DeVico, Anthony L.; Ray, Krishanu; Lewis, George K.; Pazgier, Marzena

doi:10.1128/jvi.01232-15

Cited by 53 publications

(111 citation statements)

References 75 publications

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“…3), which were mainly due to on-rate effects, as evaluated by SPR. In the case of anti-cluster A antibodies, this is consistent with previous mutagenesis and structural data indicating that tryptophan 69 is localized within the cluster A epitope, contributing to the conformation of this region recognized by this family of antibodies (15,(18)(19)(20)43). However, in the case of CoRBS antibodies, these results are consistent with a model in which mutants W69G, W69A, W69I, and W69L do not spontaneously sample the CD4-bound conformation.…”

Section: Resultssupporting

confidence: 81%

“…Since it has been previously reported that the inner domain layers modulate recognition of gp120 by CD4i antibodies (15,16,30), we next examined the binding capacity of our panel of W69 gp120 variants to CD4i antibodies recognizing the coreceptor binding site (CoRBS; 17b and 48d) and anti-cluster A antibodies, known to be potent mediators of ADCC responses (A32, N5-i5, and N60-i3) (15,19,43,45,46). It was previously shown that CD4i antibodies preferentially recognize the CD4-triggered monomeric gp120, but they are still capable of binding to unliganded gp120 with roughly 10-to 20-fold lower affinities (15,18).…”

Section: Resultsmentioning

confidence: 99%

“…We also generated a double mutant in which W69 was exchanged for alanine and S115 for tryptophan. The S115 mutation was modeled on available structural information on CD4-triggered gp120 cores (19,43) with the assumption that the hydrophobicity lost due to the W69A mutation at the layer 1-layer 2 interface could be compensated for by a tryptophan at an alternative interlayer position. All mutant variants were evaluated with respect to the following properties: proteolytic processing of the gp160 precursor, association of the gp120 and gp41 subunits, CD4 binding, functional ability to mediate cellcell fusion, and virus infectivity ( Table 1).…”

Section: Resultsmentioning

confidence: 99%

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A Highly Conserved gp120 Inner Domain Residue Modulates Env Conformation and Trimer Stability

Ding

Tolbert

Prévost

et al. 2016

J Virol

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Previous studies have shown that highly conserved residues in the inner domain of gp120 are required for HIV-1 envelope glycoprotein ( We evaluated the contribution of the hydrophobicity of W69 to conformational changes of Env by replacing it with a series of residues with aliphatic or aromatic side chains of decreasing chain length. We have found that the hydrophobicity of residue 69 is important for Env processing, CD4 binding, and its transition to the CD4-bound conformation. The most deleterious effect was observed when W69 was replaced with alanine or glycine residues. However, the functions lost due to W69 mutations could be progressively restored with amino acids of increasing aliphatic chain length and fully recovered with residues bearing an aromatic ring. Interestingly, poor CD4 binding of W69A could be fully restored by introducing a compensatory mutation within layer 2 (S115W). Structural studies of HIV-1 gp120 core e W69A/S115W mutant bound to the CD4 peptide mimetic M48U1 and Fab of anti-cluster A antibody N60-i3 revealed no perturbations to the overall structure of the double mutant compared to the wild-type protein but identified higher mobility within the interface between layer 1 and layer 2, the bridging sheet region, and the CD4 binding site. HIV-1 envelope glycoproteins (Env) play a key role during the first step of viral infection. Mature HIV-1 Env trimers are the products of a proteolytic cleavage of gp160 precursor polypeptides into gp120 (SU) and gp41 (TM) subunits. Mature metastable Env is a consolidation of three gp120 with three gp41 transmembrane subunits related in a labile noncovalent manner (1). Binding of gp120 exterior subunit to its cellular receptor, CD4, initiates viral entry (2, 3). CD4 binding allows gp120 conformational rearrangement, which is required for its attachment to CCR5 or CXCR4 chemokine coreceptors (4-11), upon which further conformational changes expose the gp41 helical heptad repeat segment (HR1), resulting in the formation of the prehairpin intermediates followed by a transition to a six-helix bundle composed of HR1 and HR2. These conformational changes lead to viral and cellular membrane fusion (12)(13)(14). CD4-induced changes allow the trimer to switch from a metastable high-energy unliganded form to a low-energy stable state.Recent studies have shown that highly conserved residues in the inner domain of gp120 are required for HIV-1 Env transitions to the CD4-bound conformation and efficient CD4 binding (15,16). Moreover, among these residues, W69 was recently shown to be important for efficient Env recognition by antibody-dependent cellular cytotoxicity (ADCC)-mediating anti-cluster A antibodies and also by sera from HIV-1-infected individuals (17-20). Since W69 is located at the interface between layer 1 and layer 2 of the

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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A Highly Conserved gp120 Inner Domain Residue Modulates Env Conformation and Trimer Stability

Ding

Tolbert

Prévost

et al. 2016

J Virol

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“…Such conformational changes have been reported for both the outer and inner domains of gp120 (35)(36)(37). Here we have specifically analyzed the changes associated with the outer domain harboring the CD4 binding site itself.…”

Section: Resultsmentioning

confidence: 99%

“…In a desire to reveal structural elements that discriminate and delineate the essence of the CD4-induced (CD4i) conformational rearrangements in the HIV envelope, we and others have investigated gp120 structures using "conditional" probes, MAbs, that specifically define epitopes associated with CD4i transitions of gp120 (33)(34)(35)(36)(37)(38)(39)(40)(41). Here we describe the analysis of gp120 with a select panel of five well-established CD4i MAbs that target the core outer domain.…”

mentioning

confidence: 99%

Range of CD4-Bound Conformations of HIV-1 gp120, as Defined Using Conditional CD4-Induced Antibodies

Kaplan

Roitburd-Berman

Lewis

et al. 2016

J Virol

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The HIV envelope binds cellular CD4 and undergoes a range of conformational changes that lead to membrane fusion and delivery of the viral nucleocapsid into the cellular cytoplasm. This binding to CD4 reveals cryptic and highly conserved epitopes, the molecular nature of which is still not fully understood. The atomic structures of CD4 complexed with gp120 core molecules (a form of gp120 in which the V1, V2, and V3 loops and N and C termini have been truncated) have indicated that a hallmark feature of the CD4-bound conformation is the bridging sheet minidomain. Variations in the orientation of the bridging sheet hairpins have been revealed when CD4-liganded gp120 was compared to CD4-unliganded trimeric envelope structures. Hence, there appears to be a number of conformational transitions possible in HIV-1 monomeric gp120 that are affected by CD4 binding. The spectrum of CD4-bound conformations has been interrogated in this study by using a well-characterized panel of conditional, CD4-induced (CD4i) monoclonal antibodies (MAbs) that bind HIV-1 gp120 and its mutations under various conditions. Two distinct CD4i epitopes of the outer domain were studied: the first comprises the bridging sheet, while the second contains elements of the V2 loop. Furthermore, we show that the unliganded extended monomeric core of gp120 (core e ) assumes an intermediate CD4i conformation in solution that further undergoes detectable rearrangements upon association with CD4. These discoveries impact both accepted paradigms concerning gp120 structure and the field of HIV immunogen design. IMPORTANCE Elucidation of the conformational transitions that the HIV-1 envelope protein undergoes during the course of entry into CD4؉ cells is fundamental to our understanding of HIV biology. The binding of CD4 triggers a range of gp120 structural rearrangements that could present targets for future drug design and development of preventive vaccines. Here we have systematically interrogated and scrutinized these conformational transitions using a panel of antibody probes that share a specific preference for the CD4i conformations. These have been employed to study a collection of gp120 mutations and truncations. Through these analyses, we propose 4 distinct sequential steps in CD4i transitions of gp120 conformations, each defined by antibody specificities and structural requirements of the HIV envelope monomer. As a result, we not only provide new insights into this dynamic process but also define probes to further investigate HIV infection. V iral tropism is mediated by the specific binding of the viral spike protein to its corresponding cell surface receptor. Evolution has driven human immunodeficiency virus (HIV) to elaborate on this canonical paradigm, introducing a series of orchestrated sequential events involving two receptors: CD4 as a primary receptor (1-3) and a chemokine receptor (CXCR4 or CCR5) as a subsequent coreceptor (4-10). However, many critical details of the molecular mechanisms by which CD4 triggers a number of conformati...

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The alpha helix 1 from the first conserved region of HIV1 gp120 is reconstructed in the short NQ21 peptide

Khrustalev

Khrustaleva

Kahanouskaya

et al. 2018

Archives of Biochemistry and Biophysics

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Cocrystal Structures of Antibody N60-i3 and Antibody JR4 in Complex with gp120 Define More Cluster A Epitopes Involved in Effective Antibody-Dependent Effector Function against HIV-1

Abstract: Accumulating evidence indicates a role for

Cited by 53 publications

References 75 publications

A Highly Conserved gp120 Inner Domain Residue Modulates Env Conformation and Trimer Stability

A Highly Conserved gp120 Inner Domain Residue Modulates Env Conformation and Trimer Stability

Range of CD4-Bound Conformations of HIV-1 gp120, as Defined Using Conditional CD4-Induced Antibodies

The alpha helix 1 from the first conserved region of HIV1 gp120 is reconstructed in the short NQ21 peptide

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