Fig 1.

Similar architecture of gp120 across isolates observed by SAXS. (A and B) SAXS curves (A) and pairwise distance distribution [P(r)] plots (B) show that the four full-length gp120s are similar in shape and size. Guinier plots (A, inset) indicate that the gp120 specimens did not exhibit aggregation or interparticle effects, which would have complicated the analysis. a.u., arbitrary units. (C) DAMMIN shape reconstructions of unliganded 1084i (left) and 1157ip (right) full-length gp120 (gray envelopes), with the gp120 extended core from 3JWD.pdb and containing the V3 loop from 2B4C.pdb (blue spheres) docked into the SAXS shape envelope. The V1/V2 stem in the CD4-bound conformation does not fit into the unliganded SAXS density. Instead, a lobe of mass atop the gp120 core is attributed to V1/V2 proximal to the likely V3 position in unliganded full-length gp120 (40). Two-domain sCD4 was not present in the SAXS experiment; however, it is shown as a red ribbon to aid in the interpretation of the SAXS envelopes.