Disulfide Reduction in CD4 Domain 1 or 2 Is Essential for Interaction with HIV Glycoprotein 120 (gp120), which Impairs Thioredoxin-driven CD4 Dimerization

Cerutti, Nichole; Killick, Mark; Jugnarain, Vinesh; Papathanasopoulos, Maria A.; Capovilla, Alexio

doi:10.1074/jbc.m113.539353

Cited by 34 publications

(43 citation statements)

References 42 publications

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“…Our current findings can thus be seen as experimental conformation of the theoretical prediction that, at longer timescales, the allosteric disulfide of D2 induces conformational changes in the domain when shuffling between its redox states. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 19 Despite these insights, and others that have demonstrated how the redox state of the D2 disulfide defines the ligand-binding specificity of CD4, 30,38,47 the biological importance of CD4 domain 2 metastability remains unclear. It has been proposed that the oxidized and partially reduced forms of CD4 exist in equilibrium on the cell surface, and secretion of thioredoxin by activated T-cells facilitates the reduction of the D2 allosteric disulfide to trigger necessary conformational changes in CD4.…”

Section: Allosteric Disulfide Bond Dependent Changes In the Structurementioning

confidence: 85%

“…38 Size-exclusion chromatography on the other hand can inform about the changes to the hydrodynamic volume of a protein in its native, properly folded form, and can thus reveal the structural response of a protein when it experiences bond breakage such as disulphide reduction. With respect to 2dCD4, SEC reveals that the addition of a disulfide bond to domain 2 appears to distinctly increase the native hydrodynamic volume of the two domain protein.…”

Section: Reduction Of the D2 Disulfide Decreases The Native Hydrodynamentioning

confidence: 99%

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Human CD4 Metastability Is a Function of the Allosteric Disulfide Bond in Domain 2

et al. 2016

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CD4 is expressed on the surface of specific leukocytes where it plays a key role in the activation of immunostimulatory T-cells and acts as a primary receptor for HIV-1 entry. CD4 has four ecto-domains (D1-D4) of which D1, D2, and D4 contain disulfide bonds. Although disulfide bonds commonly serve structural or catalytic functions, a rare class of disulfide bonds possessing unusually high dihedral strain energy and a relative ease of reduction can impact protein function by shuffling their redox state. D2 of CD4 possesses one such "allosteric" disulfide. While it is becoming accepted that redox exchange of the D2 allosteric disulfide plays an essential role in regulating CD4 activity, the biophysical consequences of its reduction remain incompletely understood. By analyzing the hydrodynamic volume, secondary structure, and thermal stability of the reduced and nonreduced forms of the single D1 and D2 domains, as well as the various redox isomers of two domain CD4, we have shown that ablation of the allosteric disulfide bond in domain 2 results in both a favorable structural collapse and an increase in the stability of CD4. Conversely, ablating the structural disulfide of D1 results in destabilizing structural rearrangements in CD4. These findings expand our understanding of the mechanisms by which oxidoreduction of the D2 allosteric disulfide regulates CD4 function; they reveal the intrinsic disulfide-dependent metastability of D2 and illustrate that redox shuffling of the allosteric disulfide results in previously undescribed conformational changes in CD4 that are likely important for its interaction with its protein partners.

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Section: Allosteric Disulfide Bond Dependent Changes In the Structurementioning

confidence: 85%

Section: Reduction Of the D2 Disulfide Decreases The Native Hydrodynamentioning

confidence: 99%

Human CD4 Metastability Is a Function of the Allosteric Disulfide Bond in Domain 2

et al. 2016

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“…It is well known that the intramolecular disulfide bond in D2 behaves as an allosteric disulfide due to its high torsional strain. Cleavage of this disulfide is critical for HIV entry, and it is promoted by Trx (73) but not PDI (74). Trx-mediated bond cleavage also promotes homodimer formation, likely through two intermolecular disulfides between Cys130 in one monomer and Cys159 in the other.…”

Section: Extracellular Protein Redox Switchesmentioning

confidence: 99%

Thiol–Disulfide Exchange Reactions in the Mammalian Extracellular Environment

Khosla

2016

Annu. Rev. Chem. Biomol. Eng.

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Disulfide bonds represent versatile posttranslational modifications whose roles encompass the structure, catalysis, and regulation of protein function. Due to the oxidizing nature of the extracellular environment, disulfide bonds found in secreted proteins were once believed to be inert. This notion has been challenged by the discovery of redox-sensitive disulfides that, once cleaved, can lead to changes in protein activity. These functional disulfides are twisted into unique configurations, leading to high strain and potential energy. In some cases, cleavage of these disulfides can lead to a gain of function in protein activity. Thus, these motifs can be referred to as switches. We describe the couples that control redox in the extracellular environment, examine several examples of proteins with switchable disulfides, and discuss the potential applications of disulfides in molecular biology.

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“…The importance of thiol–disulfide interaction in lysis may be related to the role of gp120 disulfide exchange in HIV cell infection. 10–12 …”

Section: Introductionmentioning

confidence: 99%

Disulfide Sensitivity in the Env Protein Underlies Lytic Inactivation of HIV-1 by Peptide Triazole Thiols

Bailey

Sundaram

et al. 2015

ACS Chem. Biol.

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We investigated the mode of action underlying lytic inactivation of HIV-1 virions by peptide triazole thiol (PTT), in particular the relationship between gp120 disulfides and the C-terminal cysteine-SH required for virolysis. Obligate PTT dimer obtained by PTT SH cross-linking and PTTs with serially truncated linkers between pharmacophore isoleucine–ferrocenyltriazole-proline–tryptophan and cysteine-SH were synthesized. PTT variants showed loss of lytic activity but not binding and infection inhibition upon SH blockade. A disproportionate loss of lysis activity vs binding and infection inhibition was observed upon linker truncation. Molecular docking of PTT onto gp120 argued that, with sufficient linker length, the peptide SH could approach and disrupt several alternative gp120 disulfides. Inhibition of lysis by gp120 mAb 2G12, which binds at the base of the V3 loop, as well as disulfide mutational effects, argued that PTT-induced disruption of the gp120 disulfide cluster at the base of the V3 loop is an important step in lytic inactivation of HIV-1. Further, PTT-induced lysis was enhanced after treating virus with reducing agents dithiothreitol and tris (2-carboxyethyl)phosphine. Overall, the results are consistent with the view that the binding of PTT positions the peptide SH group to interfere with conserved disulfides clustered proximal to the CD4 binding site in gp120, leading to disulfide exchange in gp120 and possibly gp41, rearrangement of the Env spike, and ultimately disruption of the viral membrane. The dependence of lysis activity on thiol–disulfide interaction may be related to intrinsic disulfide exchange susceptibility in gp120 that has been reported previously to play a role in HIV-1 cell infection.

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Disulfide Reduction in CD4 Domain 1 or 2 Is Essential for Interaction with HIV Glycoprotein 120 (gp120), which Impairs Thioredoxin-driven CD4 Dimerization

Cited by 34 publications

References 42 publications

Human CD4 Metastability Is a Function of the Allosteric Disulfide Bond in Domain 2

Human CD4 Metastability Is a Function of the Allosteric Disulfide Bond in Domain 2

Thiol–Disulfide Exchange Reactions in the Mammalian Extracellular Environment

Disulfide Sensitivity in the Env Protein Underlies Lytic Inactivation of HIV-1 by Peptide Triazole Thiols

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