Structural investigation of the HIV-1 envelope glycoprotein gp160 cleavage site 3: Role of site-specific mutations

摘要

Proteolytic processing of HIV gp 160 to produce gp 120 and gp41 is performed by PC enzymes. This process is a prerequisite for the virus infectivity, since both gp120 and gp41 participate in the virus HIV-1 entry mechanism. The structure of the gp120/gp47 junction remains to be elucidated, and the structural features required for molecular recognition between HIV-1 gp160 and proteolytic enzymes have not been clarified. Furin is the best PC candidate for the gp 160 proteolytic processing known to date. In previous studies on model peptides, we hove shown the relevance of an N-terminal helix for the proper recognition of the gp160 processing site by furin. Here we analyze the effect of point mutations in peptides locking a regular N-terminal helix. To this end, we present the structure-activity characterization of three peptide analogues of the HIV gp 160 processing site that all present mutations in proline at positions P3 and/or P2', while sharing the some N-terminal sequence, containing helix-breaking D-amino acids. Conformational analysis of the peptides was carried out in solution by NMR techniques, and furin's efficiency in cleaving them was measured. Structural findings are presented and discussed in relation to the different exhibited activity.