IgG1 conformational behavior: elucidation of the N-glycosylation role via molecular dynamics

Effect of Fc core fucosylation and light chain isotype on IgG1 flexibility

“…The results (Fig. 1d) show that adalimumab G0F has a lower distance in terms of median value (3.1 nm) and therefore a closed Fc domain than adalimumab G0 (4.8 nm), as reported in our previous work 20 . Avelumab species show instead very similar distributions, with median values of 3.7 nm (G0) and 4.1 nm (G0F), comparable to adalimumab G0, supporting the hypothesis of very similar behaviors of avelumab forms.…”

“…4a), as for the cMD simulations, it was observed that while κ mAbs prefer an open Fc conformation with CH2 distance values globally ranging between 4 and 6 nm, the λ ones prefer a closed Fc structure, with CH2 distances between 2 and 4.5 nm. Moreover, the results show that the Fc domain tends to stay in a more closed conformation in G0F species than in G0, according with that previously reported 20 . This data are aligned with the analysis of minimum distance between carbohydrate chains reported in Fig.…”

“…Two representatives of κ and λ IgG1 LCs, adalimumab and avelumab, in their G0 and G0F forms, were investigated and two effects impacting the flexibility of the mAbs were observed: the "fucosylation effect", that has been already extensively described 1,[11][12][13][15][16][17] , and the "LC effect" that we report here for the first time. As already hypothesized in our previous work 20 and in line with the role of glycosylation in influencing the flexibility of IgG1 demonstrated by Spiteri et al 21 , the "fucosylation effect" impacts on the Y/T-shaped conformation preference and on the position of glycans inside/outside the Fc. The "LC effect", instead, was found to modulate the Fab rotation and the Fc opening, as well as contributing to the Y/T-shaped conformation stability, suggesting another player in the conformational features of these biomolecules.…”

“…Accordingly, the analysis was focused on the variation of θ angle in the last 7000 frames. This angle, as already shown 20 , represents the propensity of Fab domains to come close to the Fc, allowing the classification of Y-(θ < 85°) or T-shaped (θ ≥ 85°) conformations. Figure 1a shows a clear tendency of G0F adalimumab to stay in a T-shaped conformation, since for the 30% of time both Fab present θ ≥ 85°.…”

“…Some studies 18,19 , have proposed hypotheses to explain the fucosylation effect on the effector functions, but focusing only on the Fc without considering the role of the hinge and Fab domains. In our previous work 20 , we proposed that the presence of fucose can modulate the conformational behavior of the whole mAb inducing a preference for a T-shaped conformation, in principle less suitable for receptor binding. In agreement with our previous results, Spiteri et al have demonstrated how glycans can introduce structural constraints, by a comparison of glycosylated and aglycosylated IgG1.…”