Structural investigation of the HIV-1 envelope glycoprotein gp160 cleavage site, 2: relevance of an N-terminal helix.
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.
Oliva
Romina
R
Dipartimento di Chimica, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli, Italy.
Falcigno
Lucia
L
D'Auria
Gabriella
G
Dettin
Monica
M
Scarinci
Claudia
C
Pasquato
Antonella
A
Di Bello
Carlo
C
Paolillo
Livio
L
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D002942:Circular Dichroism; D016384:Consensus Sequence; D045683:Furin; D019302:HIV Envelope Protein gp160 / Q000737:chemistry* / Q000378:metabolism; D015658:HIV Infections / Q000378:metabolism / Q000821:virology; D015497:HIV-1 / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013381:Subtilisins / Q000737:chemistry* / Q000378:metabolism
D019302:HIV Envelope Protein gp160; D010446:Peptide Fragments; D013381:Subtilisins; D045683:Furin