4GT7

An engineered disulfide bond reversibly traps the IgE-Fc3-4 in a closed, non-receptor binding conformation

Summary for 4GT7

• Entry DOI: 10.2210/pdb4gt7/pdb
• Descriptor: Ig epsilon chain C region, alpha-D-mannopyranose-(1-3)-[alpha-D-mannopyranose-(1-6)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-6)-beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (4 entities in total)
• Functional Keywords: immunoglobulin, antibody, ige, fc fragment, immune system, fc receptor
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 4
• Total formula weight: 102360.71

Authors

Wurzburg, B.A.,Kim, B.K.,Jardetzky, T.S. (deposition date: 2012-08-28, release date: 2012-09-12, Last modification date: 2020-07-29)

Primary citation

Wurzburg, B.A.,Kim, B.,Tarchevskaya, S.S.,Eggel, A.,Vogel, M.,Jardetzky, T.S.
An engineered disulfide bond reversibly traps the IgE-Fc3-4 in a closed, nonreceptor binding conformation.
J.Biol.Chem., 287:36251-36257, 2012

PubMed Abstract: IgE antibodies interact with the high affinity IgE Fc receptor, FcεRI, and activate inflammatory pathways associated with the allergic response. The IgE-Fc region, comprising the C-terminal domains of the IgE heavy chain, binds FcεRI and can adopt different conformations ranging from a closed form incompatible with receptor binding to an open, receptor-bound state. A number of intermediate states are also observed in different IgE-Fc crystal forms. To further explore this apparent IgE-Fc conformational flexibility and to potentially trap a closed, inactive state, we generated a series of disulfide bond mutants. Here we describe the structure and biochemical properties of an IgE-Fc mutant that is trapped in the closed, non-receptor binding state via an engineered disulfide at residue 335 (Cys-335). Reduction of the disulfide at Cys-335 restores the ability of IgE-Fc to bind to its high affinity receptor, FcεRIα. The structure of the Cys-335 mutant shows that its conformation is within the range of previously observed, closed form IgE-Fc structures and that it retains the hydrophobic pocket found in the hinge region of the closed conformation. Locking the IgE-Fc into the closed state with the Cys-335 mutation does not affect binding of two other IgE-Fc ligands, omalizumab and DARPin E2_79, demonstrating selective blocking of the high affinity receptor binding.

PubMed: 22948141
DOI: 10.1074/jbc.M112.407502

Experimental method

X-RAY DIFFRACTION (2.61 Å)