3v8c
Crystal structure of monoclonal human anti-rhesus D Fc IgG1 t125(yb2/0) double mutant (H310 and H435 in K)
Structural highlights
DiseaseIGHG1_HUMAN Defects in IGHG1 are a cause of multiple myeloma (MM) [MIM:254500. MM is a malignant tumor of plasma cells usually arising in the bone marrow and characterized by diffuse involvement of the skeletal system, hyperglobulinemia, Bence-Jones proteinuria and anemia. Complications of multiple myeloma are bone pain, hypercalcemia, renal failure and spinal cord compression. The aberrant antibodies that are produced lead to impaired humoral immunity and patients have a high prevalence of infection. Amyloidosis may develop in some patients. Multiple myeloma is part of a spectrum of diseases ranging from monoclonal gammopathy of unknown significance (MGUS) to plasma cell leukemia. Note=A chromosomal aberration involving IGHG1 is found in multiple myeloma. Translocation t(11;14)(q13;q32) with the IgH locus. Translocation t(11;14)(q13;q32) with CCND1; translocation t(4;14)(p16.3;q32.3) with FGFR3; translocation t(6;14)(p25;q32) with IRF4. FunctionPublication Abstract from PubMedIn the present study, we show that histidines 310 and 435 at the CH2-CH3 interface of the Fc portion of human IgG1 can coordinate a Zn2+ and participate in the control of the CH2-CH2 interdomain opening. Structures obtained in the absence of Zn2+ have a reduced interdomain gap that likely hamper FcgammaR binding. This closed conformation of the Fc is stabilized by inter-CH2 domain sugar contacts. Zinc appears to counteract the sugar mediated constriction, suggesting that zinc could be an important control factor in IgG1/FcgammaR interactions. The results of binding studies performed in the presence of EDTA on FcgammaR expressing cells supports this hypothesis. When a mutated Fc fragment, in which histidines 310 and 435 have been substituted by lysines (Fc H/K), was compared with the wild-type Fc in crystallographic studies, we found that the mutations leave the interface unaltered but have a long-range effect on the CH2 interdomain separation. Moreover, these substitutions have a differential effect on the binding of IgG1 to Fcgamma receptors and their functions. Interaction with the inhibitory FcgammaRIIB is strongly perturbed by the mutations and mutant IgG1 H/K only weakly engages this receptor. By contrast, higher affinity FcgammaR are mostly unaffected. Effect of zinc on human IgG1 and its FcgammaR interactions.,Siberil S, Menez R, Jorieux S, de Romeuf C, Bourel D, Fridman WH, Ducancel F, Stura EA, Teillaud JL Immunol Lett. 2012 Mar 30;143(1):60-9. PMID:22553781[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References | ||||||||||||||||||||
