FIG 9.
Conformational flexibility of SOSIP.664-His and gp140UNC-Fd-His proteins. Deuterium uptake plots are shown for selected peptides from the following purified Env proteins: BG505 SOSIP.664 (gray), 92UG037.8 gp120 (orange), 92UG037.8 SOSIP.664-His (red), CZA97.012 SOSIP.664-His (blue), 92UG037.8 gp140UNC-Fd-His (green), and CZA97.012 gp140UNC-Fd-His (purple). The position of each peptide is shown on the crystal structure of the BG505 SOSIP.664 trimer (PDB accession no. 4TVP) on the top, with sequence positions shown in parentheses (relative to HXB2 numbering) in the bottom right-hand corner of each graph. Error bars show the standard deviations from duplicate measurements, which in most cases are too small to see. The tetrapeptide (PPPI) was added to each sample to ensure that exchange conditions were identical among all samples compared. The 92UG037.8 and CZA97.012 SOSIP.664-His trimers were purified by the PGT145/SEC and PGT151/SEC methods, respectively, and the two gp140UNC-Fd-His proteins were purified via Ni-NTA/SEC. The data for the BG505 SOSIP.664 and 92UG037.8 gp120 proteins were derived from prior reports (41, 48).