Abstract

Poster Presentations

Day 3, May 13（Wed.）　　Poster (1008/09)

2P-45（3B-O14-1550）　　PDF

Interaction analysis of IgG1 and FcγRIIIa by HDX-MS

(¹Osaka Univ., ²Nagoya City Univ., ³ExCELLS, ⁴AIST, ⁵Tokushima Univ., ⁶Thermo Fisher, ⁷Nagoya Univ.)
^oYuki Yamaguchi¹, Rina Yogo^2,3, Hiroki Watanabe³, Hirokazu Yagi², Tadashi Satoh², Mahito Nakanishi⁴, Masayoshi Onitsuka⁵, Takeshi Omasa¹, Natsumi Wakaizumi¹, Mari Shimada¹, Takahiro Maruno¹, Tetsuo Torisu¹, Shio Watanabe⁶, Daisuke Higo⁶, Takayuki Uchihashi^3,7, Saeko Yanaka^2,3, Koichi Kato^2,3, Susumu Uchiyama^1,3

Interaction of immunoglobulin G1 (IgG1) and FcγRIIIa expressed on the natural killer cells promotes antibody-dependent cellular cytotoxicity (ADCC). In previous studies, the structure of the IgG Fc fragments and FcγRIII complex has been reported, however, the complex structure of IgG full-body and FcγRIII remains elusive. Here, we performed hydrogen/deuterium exchange mass spectrometry (HDX-MS) to identify the interaction sites between IgG1 full-body and FcγRIIIa. HDX-MS monitors chronological HDX rates of amide hydrogens by MS-based peptide mapping which is used for measuring the mass shift caused by HDX. HDX of the interacting regions in complex state were slower than free state. Comparison of HDX in IgG1 with that in IgG1-FcγRIIIa complex showed that HDX rates of some segments in the Fab region decreased upon the binding to FcγRIIIa as well as the previously reported binding site in the Fc region. For FcγRIIIa, changes in HDX rate were observed in some regions in domain 1 by the binding to IgG1. These results indicate that not only the Fc region of IgG1 but also the Fab region are responsible for the binding of IgG1 to FcγR. Our findings will offer the new target for the developments of ADCC-enhanced therapeutic antibodies