Fig. 6: Transfer of stabilizing substitutions to other paramyxovirus F proteins.

A Sequence alignment of the HRB heptad register of selected F proteins. The a and d positions are highlighted in cyan, with the suboptimal residues at positions 470 and 477 highlighted in red (numbering according to RV3). B Neighbor joining phylogenetic tree of representative paramyxovirus F proteins. C, D Expression of RV1 F protein variants in supernatant as measured by BLI using immobilized 3 × 1 antibody. The initial slope, V0, at the start of binding is plotted as the average of three independent transfections; error bars represent the SD. RV1 F substitutions A44P, E170P, Q171P, S473V, and A480V substitutions are the equivalents of the following substitutions in RV3, respectively: S41P, N167P, L168P, S470V, and S477V. E Analytical SEC trace of wildtype and stabilized (A44P + E170P + Q171P + S473V + A480V) RV1 F in cell supernatant. The trimer (T) peak is indicated. F Analytical SEC-MALS of purified stabilized RV1 preF. Expression of NiV F protein variants in supernatant as measured by BLI using immobilized 5B3 antibody (G, I, K), or by analytical SEC (H, J, L). For BLI, the initial slope, V0, at the start of binding is plotted as the average of three independent transfections; error bars represent the SD. NiV F substitutions K49P, K167P, S470V, and A477V are the equivalents of the following substitutions in RV3, respectively: S41P, N167P, S470V, and S477V.