Alternative conformations of a major antigenic site on RSV F

Jones, Harrison G.; Battles, Michael B.; Lin, Chun-Chi; Bianchi, Siro; Corti, Davide; McLellan, Jason S.

In addition, the extent to which the antibodies interact with the F2 subunit varies greatly between the three antibodies. The RSD5-GL interface with F2 accounts for 21% of the buried surface area on prefusion RSV F and includes two hydrogen bonds with Lys65. The D25 interface with F2 contributes 23% of the buried surface area and includes five hydrogen bonds to four residues within Asn63-Lys68. In contrast, the interface between AM22 and F2 accounts for only 9% of the buried surface area on prefusion RSV F, and AM22 forms no hydrogen bonds or salt bridges with F2. Thus, whereas RSD5-GL and D25 make several contacts with the F2 loop, AM22 interacts almost exclusively with the F1 subunit. and top views in ribbon-and-stick representation, colored as in (A), highlighting the β-sheet hydrogen bond interactions between F1 and the CDR H3 of AM22. The light chain was hidden in the lower-left panel and both panels on the right for clarity. For stick models, oxygen atoms are colored red, nitrogen blue, and sulfur yellow. (C) The amino acid sequence of RSV F site Ø is shown for both strain A2 and strain B9320. Diamond symbols above each residue indicate a contact between AM22 and prefusion RSV F strain A2 based upon PDBePISA analysis of the crystal structure.