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.
Department of Antibody Discovery and Protein Engineering, MedImmune Inc., One MedImmune Way, Gaithersburg, MD 20878, USA.
Vaheh
V
Oganesyan
Changshou
C
Gao
Lena
L
Shirinian
Herren
H
Wu
William F
WF
Dall'Acqua
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