Structural Investigation of the HIV-1 Envelope Glycoprotein gp160 Cleavage Site, 2: Relevance of an N-Terminal Helix

• Published in: Chembiochem : a European journal of chemical biology 2003-08, Vol.4 (8), p.727-733
• Main Authors: Oliva, Romina, Falcigno, Lucia, D′Auria, Gabriella, Dettin, Monica, Scarinci, Claudia, Pasquato, Antonella, Di Bello, Carlo, Paolillo, Livio
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Catalytic Domain; Circular Dichroism; conformation analysis; Consensus Sequence; Furin; glycoprotein gp160; gp160; HIV; HIV Envelope Protein gp160 - chemistry; HIV Envelope Protein gp160 - metabolism; HIV Infections - metabolism; HIV Infections - virology; HIV-1 - chemistry; Human immunodeficiency virus 1; Humans; Models, Molecular; molecular modeling; Molecular Sequence Data; NMR spectroscopy; Nuclear Magnetic Resonance, Biomolecular; Peptide Fragments - chemistry; Protein Conformation; Sequence Homology, Amino Acid; Subtilisins - chemistry; Subtilisins - metabolism
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.200200541

Proteolytic activation of the HIV-1 envelope glycoprotein gp160 is selectively performed by the proprotein convertase furin at the C-terminus of the sequence R508-E-K-R511 (site 1), in spite of the presence of another consensus sequence, Lys500-Ala-Lys-Arg503 (site 2). On the basis of the solution structural analysis of the synthetic peptide p498, spanning the gp160 sequence Pro498-Gly516, we previously suggested a possible role of an N-terminal helix in regulating the exposure and accessibility of the gp160 physiological cleavage site, enclosed in a loop. Here we report on the activity and conformation of the 23-residue peptide h-REKR, designed to exhibit a large N-terminal helix, followed by the gp160 native sequence, Arg508-Gly516. h-REKR is digested by furin with high efficiency, comparable to the full native p498. Circular dichroism analyses, in mixtures from pure water to 98 % trifluoroethanol, outline a significant content of helical structure in the peptide conformation. The molecular model obtained from NMR data collected in trifluoroethanol/water, by means of DYANA and AMBER simulations, indeed has helical structure on a large N-terminal segment. Such a long helix does not seem to affect the loop conformation of the C-terminal site 1-containing sequence, which exhibits the same proton chemical shifts already observed for the full native p498.