The weaker-binding Fc γ receptor IIIa F158 allotype retains sensitivity to N-glycan composition and exhibits a destabilized antibody-binding interface

Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved..

Antibodies engage Fc γ receptors (FcγRs) to elicit healing cellular immune responses following binding to a target antigen. Fc γ receptor IIIa/CD16a triggers natural killer cells to destroy target tissues with cytotoxic proteins and enhances phagocytosis mediated by macrophages. Multiple variables affect CD16a antibody-binding strength and the resulting immune response, including a genetic polymorphism. The predominant CD16a F158 allotype binds antibodies with less affinity than the less common V158 allotype. This polymorphism likewise affects cellular immune responses and clinical efficacy of antibodies relying on CD16a engagement, though it remains unclear how V/F158 affects CD16a structure. Another relevant variable shown to affect affinity is composition of the CD16a asparagine-linked (N)-glycans. It is currently not known how N-glycan composition affects CD16a F158 affinity. Here, we determined N-glycan composition affects the V158 and F158 allotypes similarly, and N-glycan composition does not explain differences in V158 and F158 binding affinity. Our analysis of binding kinetics indicated the N162 glycan slows the binding event, and shortening the N-glycans or removing the N162 glycan increased the speed of binding. F158 displayed a slower binding rate than V158. Surprisingly, we found N-glycan composition had a smaller effect on the dissociation rate. We also identified conformational heterogeneity of CD16a F158 backbone amide and N162 glycan resonances using NMR spectroscopy. Residues exhibiting chemical shift perturbations between V158 and F158 mapped to the antibody-binding interface. These data support a model for CD16a F158 with increased interface conformational heterogeneity, reducing the population of binding-competent forms available and decreasing affinity.

Medienart:

E-Artikel

Erscheinungsjahr:

2022

Erschienen:

2022

Enthalten in:

Zur Gesamtaufnahme - volume:298

Enthalten in:

The Journal of biological chemistry - 298(2022), 9 vom: 01. Sept., Seite 102329

Sprache:

Englisch

Beteiligte Personen:

Kremer, Paul G [VerfasserIn]
Barb, Adam W [VerfasserIn]

Links:

Volltext

Themen:

7006-34-0
Adaptive immune system
Antigens, CD1
Asparagine
CD1a antigen
FCGR3A protein, human
Glycobiology
Glycoprotein
Immunoglobulin G
Journal Article
NMR spectroscopy
Polysaccharides
Receptors, IgG
Research Support, N.I.H., Extramural
Surface plasmon resonance

Anmerkungen:

Date Completed 29.09.2022

Date Revised 18.10.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.jbc.2022.102329

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM344414663