Campus Units

Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of

Document Type

Article

Publication Version

Published Version

Publication Date

3-9-2018

Journal or Book Title

Journal of Biological Chemistry

Volume

293

Issue

10

First Page

3477

Last Page

3489

DOI

10.1074/jbc.RA117.001207

Abstract

CD16a/Fc γ receptor IIIa is the most abundant antibody Fc receptor expressed on human natural killer (NK) cells and activates a protective cytotoxic response following engagement with antibody clustered on the surface of a pathogen or diseased tissue. Therapeutic monoclonal antibodies (mAbs) with greater Fc-mediated affinity for CD16a show superior therapeutic outcome; however, one significant factor that promotes antibody–CD16a interactions, the asparagine-linked carbohydrates (N-glycans), remains undefined. Here, we purified CD16a from the primary NK cells of three donors and identified a large proportion of hybrid (22%) and oligomannose N-glycans (23%). These proportions indicated restricted N-glycan processing and were unlike those of the recombinant CD16a forms, which have predominantly complex-type N-glycans (82%). Tethering recombinant CD16a to the membrane by including the transmembrane and intracellular domains and via coexpression with the Fc ϵ receptor γ–chain in HEK293F cells was expected to produce N-glycoforms similar to NK cell–derived CD16a but yielded N-glycoforms different from NK cell–derived CD16a and recombinant soluble CD16a. Of note, these differences in CD16a N-glycan composition affected antibody binding: CD16a with oligomannose N-glycans bound IgG1 Fc with 12-fold greater affinity than did CD16a having primarily complex-type and highly branched N-glycans. The changes in binding activity mirrored changes in NMR spectra of the two CD16a glycoforms, indicating that CD16a glycan composition also affects the glycoprotein's structure. These results indicated that CD16a from primary human NK cells is compositionally, and likely also functionally, distinct from commonly used recombinant forms. Furthermore, our study provides critical evidence that cell lineage determines CD16a N-glycan composition and antibody-binding affinity.

Comments

This research was originally published in the Journal of Biological Chemistry. Patel, Kashyap R., Jacob T. Roberts, Ganesh P. Subedi, and Adam W. Barb. "Restricted processing of CD16a/Fc γ receptor IIIa N-glycans from primary human NK cells impacts structure and function." Journal of Biological Chemistry 293, no. 10 (2018): 3477-3489. © the American Society for Biochemistry and Molecular Biology. doi: 10.1074/jbc.RA117.001207.

Copyright Owner

The American Society for Biochemistry and Molecular Biology, Inc.

Language

en

File Format

application/pdf

Share

COinS