Membrane-perturbing domains of HIV type 1 glycoprotein 41.
Structural and functional studies were performed to assess the membrane actions of peptides based on HIV-1 glycoprotein 41,000 (gp41). Previous site-directed mutagenesis of gp41 has shown that amino acid changes in either the N-terminal fusion or N-leucine zipper region depressed viral infection and syncytium formation, while modifications in the C-leucine zipper domain both increased and decreased HIV fusion. Here, synthetic peptides were prepared corresponding to the N-terminal fusion region (FP-I; gp41 residues 519-541), the nearby N-leucine zipper domain (DP-107; gp41 residues 560-597), and the C-leucine zipper domain (DP-178; gp41 residues 645-680). With erythrocytes, FP-I or DP-107 induced dose-dependent hemolysis and promoted cell aggregation; FP-I was more hemolytic than DP-107, but each was equally effective in aggregating cells. DP-178 produced neither hemolysis nor aggregation, but blocked either FP-I- or DP-107-induced hemolysis and aggregation. Combined with previous nuclear magnetic resonance and Fourier transform infrared spectroscopic results, circular dichroism (CD) spectroscopy showed that the alpha-helicity for these peptides in solution decreased in the order: DP-107 >> DP-178 > FP-I. CD analysis also indicated binding of DP-178 to either DP-107 or FP-I. Consequently, DP-178 may inhibit the membrane actions mediated by either FP-I or DP-107 through direct peptide interactions in solution. These peptide results suggest that the corresponding N-terminal fusion and N-leucine zipper regions participate in HIV infection, by promoting membrane perturbations underlying the merging of the viral envelope with the cell surface. Further, the C-leucine zipper domain in "prefusion" HIV may inhibit these membrane activities by interacting with the N-terminal fusion and N-leucine zipper domains in unactivated gp41. Last, exogenous DP-178 may bind to the N-terminal and N-leucine zipper domains of gp41 that become exposed on HIV stimulation, thereby preventing the fusogenic actions of these gp41 regions leading to infection.
Mobley
P W
PW
Chemistry Department, California State Polytechnic University, Pomona 91768, USA.
Pilpa
R
R
Brown
C
C
Waring
A J
AJ
Gordon
L M
LM
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004903:Erythrocyte Aggregation / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008561:Membrane Fusion / Q000187:drug effects*; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*
D015700:HIV Envelope Protein gp41; D010455:Peptides