Identification of HIV-1 gp120-binding sites on SRCR1, a subdomain of gp340

摘要

Soluble gp340 inhibits HIV-1 infection through interaction with HIV-1 Env gp120. Studies have shown that the first SRCR domain of gp340 mediates the inhibitory activity and that the V3 loop of HIV-1 gp120 interacts with gp340/SRCR1. Through homology modeling and docking analysis of SRCR1 to a gp120-CD4-17b antibody complex, we identified that three loop regions containing polar or acidic residues directly interacted with gp120. These regions were distal in the primary sequence but in close proximity in the folded protein. Meanwhile we synthesized a series of biolinylated peptides of the SRCR1 domain to test the modeling predictions in a solid phase ELISA. Binding analysis confirmed the predicted gp120-binding sites. The binding surfaces involved in the interaction between HIV-1 Env gp120 and SRCR1 represent potential targets for the development of entry inhibitors and specific microbicides.