Structural characterization of a human Fc fragment engineered for lack of effector functions.
The first three-dimensional structure of a human Fc fragment genetically engineered for the elimination of its ability to mediate antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity is reported. When introduced into the lower hinge and CH2 domain of human IgG1 molecules, the triple mutation L234F/L235E/P331S ('TM') causes a profound decrease in their binding to human CD64, CD32A, CD16 and C1q. Enzymatically produced Fc/TM fragment was crystallized and its structure was solved at a resolution of 2.3 A using molecular replacement. This study revealed that the three-dimensional structure of Fc/TM is very similar to those of other human Fc fragments in the experimentally visible region spanning residues 236-445. Thus, the dramatic broad-ranging effects of TM on IgG binding to several effector molecules cannot be explained in terms of major structural rearrangements in this portion of the Fc.
Oganesyan
Vaheh
V
Department of Antibody Discovery and Protein Engineering, MedImmune Inc., One MedImmune Way, Gaithersburg, MD 20878, USA.
Gao
Changshou
C
Shirinian
Lena
L
Wu
Herren
H
Dall'Acqua
William F
WF
D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001666:Binding Sites, Antibody / Q000235:genetics; D015922:Complement C1q / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D015202:Protein Engineering; D017452:Receptors, IgG / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007141:Immunoglobulin Fc Fragments; D017452:Receptors, IgG; D011994:Recombinant Proteins; D015922:Complement C1q