Room temperature structure of human IgG4-Fc from crystals analysed in situ

Davies, Anna M.; Rispens, Theo; Heer, Pleuni Ooijevaar-de; Aalberse, Rob C.; Sutton, Brian J.

doi:10.1016/j.molimm.2016.11.021

Cited by 8 publications

(5 citation statements)

References 26 publications

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“…Evidence suggests that FAE and Fc-Fc reactivity may involve the same molecular structure on IgG4 molecule. 10 Davies et al 11 12 resolved the crystal structure of IgG4 Fc fragment revealing a unique molecular conformation supporting its Fc binding property. Recent interests in IgG4-related diseases unveiled a wide range of pathologies with a common phenomenon of often increased IgG4 concentration in the serum and IgG4-postive plasma cells in the affected organs accompanied by local inflammation and fibrosis, but its pathogenic mechanism is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

An immune evasion mechanism with IgG4 playing an essential role in cancer and implication for immunotherapy

Wang

Zhao

et al. 2020

J Immunother Cancer

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BackgroundRecent impressive advances in cancer immunotherapy have been largely derived from cellular immunity. The role of humoral immunity in carcinogenesis has been less understood. Based on our previous observations we hypothesize that an immunoglobulin subtype IgG4 plays an essential role in cancer immune evasion.MethodsThe distribution, abundance, actions, properties and possible mechanisms of IgG4 were investigated with human cancer samples and animal tumor models with an extensive array of techniques both in vitro and in vivo.ResultsIn a cohort of patients with esophageal cancer we found that IgG4-containing B lymphocytes and IgG4 concentration were significantly increased in cancer tissue and IgG4 concentrations increased in serum of patients with cancer. Both were positively related to increased cancer malignancy and poor prognoses, that is, more IgG4 appeared to associate with more aggressive cancer growth. We further found that IgG4, regardless of its antigen specificity, inhibited the classic immune reactions of antibody-dependent cell-mediated cytotoxicity, antibody-dependent cellular phagocytosis and complement-dependent cytotoxicity against cancer cells in vitro, and these effects were obtained through its Fc fragment reacting to the Fc fragments of cancer-specific IgG1 that has been bound to cancer antigens. We also found that IgG4 competed with IgG1 in reacting to Fc receptors of immune effector cells. Therefore, locally increased IgG4 in cancer microenvironment should inhibit antibody-mediated anticancer responses and help cancer to evade local immune attack and indirectly promote cancer growth. This hypothesis was verified in three different immune potent mouse models. We found that local application of IgG4 significantly accelerated growth of inoculated breast and colorectal cancers and carcinogen-induced skin papilloma. We also tested the antibody drug for cancer immunotherapy nivolumab, which was IgG4 in nature with a stabilizing S228P mutation, and found that it significantly promoted cancer growth in mice. This may provide an explanation to the newly appeared hyperprogressive disease sometimes associated with cancer immunotherapy.ConclusionThere appears to be a previously unrecognized immune evasion mechanism with IgG4 playing an essential role in cancer microenvironment with implications in cancer diagnosis and immunotherapy.

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Section: Introductionmentioning

confidence: 99%

An immune evasion mechanism with IgG4 playing an essential role in cancer and implication for immunotherapy

Wang

Zhao

et al. 2020

J Immunother Cancer

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“…As a different perspective altogether, one previous structural study of the full-length IgG4 antibody suggested that the IgG4 glycans may not reside in the internal cavity of the Fc subunit, as shown in Fig 1B, but are solvent exposed [12]. That study attributed this outcome to the shorter IgG4 hinge that forced the C H 2 domains into an unorthodox conformation that differed from the available IgG4-Fc crystal structures [14][15][16]. Such a C H 2 domain rearrangement may itself reduce IgG4 function because the contact residues for FcγR and C1q binding have been displaced, however this appears unlikely.…”

Section: Plos Onementioning

confidence: 90%

“…Two detailed crystal structures for full length IgG4 (PDB ID: 5D43 and 6GFE) [12,13] provide only a single view of the IgG4 structure and not the full conformational space that the Fc and Fab subunits can occupy in solution. Six glycosylated IgG4 Fc crystal structures showed the glycans facing inward within the C H 2 domains (PDB ID: 4C54, 4C55, 5LG1, 5W5M and 5W5N) [14][15][16]. One high-resolution structure of a deglycosylated IgG4-Fc (PDB ID: 4D2N) showed that the C H 2-C H 2 domain interactions bury in part the C H 2 surface that would be solvent exposed with the glycan present [17].…”

Section: Introductionmentioning

confidence: 99%

Using atomistic solution scattering modelling to elucidate the role of the Fc glycans in human IgG4

Spiteri,

Doutch,

Rambo

et al. 2024

PLoS ONE

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Human immunoglobulin G (IgG) exists as four subclasses IgG1-4, each of which has two Fab subunits joined by two hinges to a Fc subunit. IgG4 has the shortest hinge with 12 residues. The Fc subunit has two glycan chains, but the importance of glycosylation is not fully understood in IgG4. Here, to evaluate the stability and structure of non-glycosylated IgG4, we performed a multidisciplinary structural study of glycosylated and deglycosylated human IgG4 A33 for comparison with our similar study of human IgG1 A33. After deglycosylation, IgG4 was found to be monomeric by analytical ultracentrifugation; its sedimentation coefficient of 6.52 S was reduced by 0.27 S in reflection of its lower mass. X-ray and neutron solution scattering showed that the overall Guinier radius of gyration RG and its cross-sectional values after deglycosylation were almost unchanged. In the P(r) distance distribution curves, the two M1 and M2 peaks that monitor the two most common distances within IgG4 were unchanged following deglycosylation. Further insight from Monte Carlo simulations for glycosylated and deglycosylated IgG4 came from 111,382 and 117,135 possible structures respectively. Their comparison to the X-ray and neutron scattering curves identified several hundred best-fit models for both forms of IgG4. Principal component analyses showed that glycosylated and deglycosylated IgG4 exhibited different conformations from each other. Within the constraint of unchanged RG and M1-M2 values, the glycosylated IgG4 models showed more restricted Fc conformations compared to deglycosylated IgG4, but no other changes. Kratky plots supported this interpretation of greater disorder upon deglycosylation, also observed in IgG1. Overall, these more variable Fc conformations may demonstrate a generalisable impact of deglycosylation on Fc structures, but with no large conformational changes in IgG4 unlike those seen in IgG1.

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“…In order to evaluate a role of electron transfer from Tyr to Trp +· for the initiation of Tyr side chain cleavage, we inspected the crystal structure of IgG4-Fc (PDB 4C54). , The structure revealed three Trp residues located adjacent to Tyr 373 , Tyr 436 , and Tyr 300 , respectively, displayed in Figure . Trp 313 is located 11.3 Å from Tyr 373 , Trp 381 is located 12.1 Å from Tyr 436 , and Trp 313 is located 18.1 Å from Tyr 300 .…”

Section: Discussionmentioning

confidence: 99%

Photoinduced Tyrosine Side Chain Fragmentation in IgG4-Fc: Mechanisms and Solvent Isotope Effects

2018

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Immunoglobulin gamma (IgG) monoclonal antibodies (mAbs) are glycoproteins that have emerged as powerful and promising protein therapeutics. During the process of production, storage and transportation, exposure to ambient light is inevitable, which can cause protein physical and chemical degradation. For mechanistic studies of photodegradation, we have exposed IgG4-Fc to UV light. The photoirradiation of IgG4-Fc with monochromatic UVC light at λ = 254 nm and UVB light with λmax = 305 nm in air-saturated solutions revealed multiple photoproducts originating from tyrosine side chain fragmentation at Tyr300, Tyr373, and Tyr436. Tyr side chain fragmentation yielded either Gly or various backbone cleavage products, including glyoxal amide derivatives. A mechanism is proposed involving intermediate Tyr radical cation formation, either through direct light absorption of Tyr or through electron transfer to an initial Trp radical cation, followed by elimination of quinone methide. Product formation showed either no (cleavage of Tyr373) or significant (cleavage of Tyr436) inverse product solvent isotope effects (SIEs), indicating a role for proton transfer in the cleavage mechanism of Tyr436. The role of electron transfer in the cleavage of Tyr436 was further investigated through mutation of an adjacent Trp381. This is the first observation of a photoinduced Tyr side chain cleavage reactions in a protein.

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Room temperature structure of human IgG4-Fc from crystals analysed in situ

Abstract: HighlightsRoom temperature structure of human IgG4-Fc solved from crystals analysed in situ.Structure reveals changes in crystal packing at different temperatures.Structure reveals physiologically relevant conformation of a key Fcγ receptor binding loop.

Cited by 8 publications

References 26 publications

An immune evasion mechanism with IgG4 playing an essential role in cancer and implication for immunotherapy

An immune evasion mechanism with IgG4 playing an essential role in cancer and implication for immunotherapy

Using atomistic solution scattering modelling to elucidate the role of the Fc glycans in human IgG4

Photoinduced Tyrosine Side Chain Fragmentation in IgG4-Fc: Mechanisms and Solvent Isotope Effects

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