Effects of N-Glycan Composition on Structure and Dynamics of IgG1 Fc and Their Implications for Antibody Engineering.

ABSTRACT: Immunoglobulin G1 (IgG1), a subclass of human serum antibodies, is the most widely used scaffold for developing monoclonal antibodies to treat human diseases. The composition of asparagine(N)297-linked glycans can modulate the binding affinity of IgG1 Fc to Fc ? receptors, but it is unclear how the structural modifications of N-glycan termini, which are distal from the binding interface, contribute to the affinity. Through atomistic molecular dynamics simulations of a series of sequentially truncated high-mannose IgG1 Fc glycoforms, we found that the C'E loop and the C?2-C?3 orientation are highly dynamic, and changes in N-glycan composition alter their conformational ensembles. High-mannose glycoform preferentially samples conformations that are more competent to Fc?RIIIa binding, compared to the truncated glycoforms, suggesting a role of IgG1 Fc N-glycan in optimizing the interface with the Fc receptor for efficient binding. The trajectory analyses also reveal that the N-glycan has large amplitude motions and the carbohydrate moiety interconverts between Fc-bound and unbound forms, enabling enzymatic modification of the glycan termini.

SUBMITTER: Lee HS 

PROVIDER: S-EPMC5627252 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature