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. 2009 Feb 22;16(3):265–273. doi: 10.1038/nsmb.1566

Figure 4. Structure of the H5–F10 complex.

Figure 4

(a) Structure of the H5 trimer bound to F10 (scFv). H5 is similar to the uncomplexed structure35 (pairwise r.m.s. deviation (Cα) = 1.0 and 0.63 Å for two independent trimers). HA1, HA2, the αA helix of HA2, the fusion peptide (FP) and F10 (VH and VL) are color coded. The third F10 molecule is hidden behind the stem. (b) Close-up of the epitope showing H5 as a molecular surface, with selected epitope residues labeled. The fusion peptide is in green. The tip of F10 (red ribbon) and selected CDR side chains are shown. Of 1,500 Å2 buried surface at the interface, 43% involves hydrophobic interactions. (c) Surface of the central stem region, showing two H5 monomers. One monomer has HA1 (yellow) and HA2 (blue) colored differently; the path of the FP through the epitope (red) is outlined, and mutations that do not affect binding are colored cyan (Fig. 4d). The fusion peptides (FP and FP′) are labeled in both monomers. Epitope residues are labeled white (HA2) or yellow (HA1), and the position of buried residue H1112 is shown as a black ball labeled 'H'. (d) Binding of the three nAbs to H5 mutants in the αA helix, transiently transfected into 293T cells. Note the similar response to all mutants tested. Mutations were made either to alanine or to the corresponding H7 residue; 24 h after transfection, nAbs or ferret anti-H5N1 serum was used to stain the transfected cells. Fluorescent intensity was normalized against ferret anti-serum (100%) to account for different expression levels.