HIV-1 gp41 by N-domain binds the potential receptor protein P45

Recent crystal structure analysis of HIV-1 gp41 revealed that two domains ( N- and C-domains) on gp41 play an important role in mediating membrane fusi on and HIV-1 entry. The experimental evidence that gp41 by N-domain bound t he potential receptor protein P45 could help to understand the mechanism of HIV entry. A recombinant soluble gp41 (rsgp41: Env aa539-684) could bind t o P45 in the affinity capillary electrophoresis analysis and the surface pl asmon resonance assay, In a blockade assay, peptide P1 (Env aa583-599) coul d inhibit interaction between rsgp41 and P45, while a control peptide could not. Direct binding of rsgp41, rgp41DP (aa567-648), P1 peptide and (P1)(2) peptide [(aa586-596)(2)] to P45 was examined in an ELISA assay. Rsgp41 bou nd the potential receptor protein P45 strongly, while rgp41DP and P1 as wel l as (P1)(2) could all weakly bind to P45, indicating that gp41 by N-domain weakly binds P45 and the region RILAVERYLKD located in the N-domain is def ined as the binding site for P45 binding. (C) 2000 S. Karger AG, Basel.