Biology subjects

Polozova, A.

Publications and source records attributed to Polozova, A..

2 recordsLinked to original sources

bioRxiv2026

Oligomannose Fc Glycans Reprogram the Energetic and Conformational Basis of CD16a Recognition

IgG1 Fc recognition by Fc{gamma}RIIIa/CD16a is a central determinant of antibody-dependent cellular cytotoxicity and is strongly regulated by Fc N297 glycosylation. While afucosylation and galactosylation have been extensively studied, the structural basis by which oligomannosidic Fc glycans modulate CD16a binding remains less clear, despite their prevalence in therapeutic antibodies and association with accelerated serum clearance. Here, we use all-atom molecular dynamics simulations to investigate how mannose-5 (M5) Fc glycosylation alters IgG1 Fc-CD16a recognition across Paired Biantennary (complex glycans on both Fc), asymmetric Unpaired (complex glycan on one Fc arm and M5 on the other), and Paired M5 glycoforms. Computed interaction energies reproduce the experimental trend that Paired M5 glycoforms bind CD16a less favorably than complex-type paired glycans, supporting the use of the simulations to interrogate the structural origin of this energetic hierarchy. Residue-wise energetic decomposition and contact analyses show that Paired M5 glycosylation redistributes energetic contributions away from the productive Fc-CD16a interface and reduces both protein-mediated and glycan-mediated physical contacts. Free energy surface analyses further reveal that Paired M5 systems sample broader, less stable receptor-bound conformational ensembles, while dynamic cross-correlation analysis shows reduced intra-domain and inter-domain coupling across the complex. Importantly, a single M5 glycan is sufficient to perturb productive recognition by increasing Fc-arm separation heterogeneity, reducing high-frequency protein contacts, and weakening long-range dynamic communication. Glycan identity on the receptor-proximal Fc arm emerges as a decisive determinant of binding, indicating that Fc glycan composition, pairing, and receptor-bound placement jointly encode CD16a recognition. Together, these findings provide a mechanistic framework for understanding how oligomannose Fc glycans remodel antibody-receptor engagement and suggest that asymmetric Fc glycosylation, combined with residue-level interface engineering, may offer new strategies for tuning therapeutic antibody effector function.

immunology↗

bioRxiv2026

Molecular Basis of Core Fucosylation-Dependent Modulation of IgG1-FcCD16a Binding

Core fucosylation of the IgG1 Fc N297 glycan is known to reduce binding affinity to the Fc{gamma}RIIIa (CD16a) receptor and attenuate antibody-dependent cellular cytotoxicity (ADCC), yet the structural mechanisms underlying this effect remain incompletely understood. Here, we use extensive all-atom molecular dynamics simulations to systematically investigate how Fc glycosylation modulates the structural, energetic, and dynamical landscape of the IgG1 Fc-CD16a complex across multiple systems with fucosylation and galactosylation. Relative binding free energy calculations reproduce experimentally established trends, showing that afucosylation consistently strengthens Fc-CD16a interactions. Mechanistically, dual fucosylation (on both Fc arms) increases inter-glycan packing between the Fc N297 glycans, restricts Fc glycan conformational sampling, and destabilizes the conformational organization of the CD16a N162 glycan. These glycan-mediated perturbations propagate to the protein interface. The result is reduced Fc-CD16a contact persistence, redistribution of energetically important residues away from the canonical binding interface, and broader, less stable receptor-bound conformational states. Dynamic cross-correlation analysis further reveals that afucosylated systems maintain substantially stronger coordinated motions across the Fc-CD16a assembly, whereas fucosylation disrupts long-range dynamic coupling between the receptor and antibody domains. Across these different energetic, structural, conformational, and dynamical readouts, fucosylation systematically shifts the Fc-CD16a assembly from a compact, interface-stabilized binding mode toward a more heterogeneous and weakly coupled receptor-bound ensemble. Together, our findings set forth a mechanistic basis for Fc glycosylation regulating receptor engagement through ensemble-level conformational and dynamical reorganization rather than simple local steric effects. These results provide mechanistic design principles for rational Fc glycoengineering and the development of therapeutic antibodies with enhanced effector functions. More broadly, this work highlights how glycan composition can be leveraged as a tunable molecular design parameter for engineering protein recognition, conformational stability, and immune effector function in therapeutic glycoproteins.

biophysics↗