The Membrane-Proximal Tryptophan-Rich Region of the HIV Glycoprotein, gp41, Forms a Well-Defined Helix in Dodecylphosphocholine Micelles^,

Abstract

The membrane-proximal tryptophan-rich region of the HIV transmembrane glycoprotein, gp41, plays an important role in the membrane fusion reaction. Using NMR spectroscopy, we have studied the tertiary structure of a synthetic 19-residue amidated peptide (NH2-KWASLWNWFNITNWLWYIK-CONH2) corresponding to this region in membrane-mimetic environments. Initial experiments in sodium dodecyl sulfate/H2O micelles and trifluoroethanol gave poor results, because of low solubility. However, in dodecylphosphocholine micelles, we obtained excellent 500 and 800 MHz NMR spectra, suggesting that the peptide has a preference for a zwitterionic membrane-like environment. The final NMR structures demonstrated a well-defined helical peptide with a backbone rmsd of 0.47 +/- 0.18 A. Four of the five tryptophan residues, as well as the tyrosine residue, formed a "collar" of aromatic residues along the axial length of the helix. By analogy to related tryptophan-rich antimicrobial peptides, the structure indicates that the aromatic residues of the HIV peptide are positioned within the membrane-water interface of a phospholipid bilayer. This is confirmed by the observation of direct NOEs between the aromatic residues of the peptide to the headgroup and interfacial protons of prototonated dodecylphosphocholine. The bulk of the polar residues are positioned on one face of this structure, with the hydrophobic phenylalanine side chain on the opposing face, forming an amphipathic structure. This work shows that the Trp-rich membrane-proximal region of HIV and related viruses can bind to the surfaces of zwitterioninc membranes in a "Velcro-like" manner.

Immunogenicity of recombinant human immunodeficiency virus type 1-like particles expressing gp41 derivatives in a pre-fusion state

“…To date, few immunogenicity studies focused on the 4E10 epitope have been reported. The extended helical structure of an MPER peptide, KWASLWNWFNITNWLWYIK in DPC micelles was also revealed by an NMR study offering a model of possible interaction of this region with the membrane [45]. More recently, a crystal structure of a 4E10 Fab in complex with a peptide bearing the sequence, WNWFDITNW revealed its major contact residue segment, WFDIT to be in a helical conformation [46].…”

Addition of a cholesterol group to an HIV-1 peptide fusion inhibitor dramatically increases its antiviral potency

“…To this aim, we have chosen C34 instead of T20 because the former has more potent antiviral activity in vitro, whereas the latter already includes a hydrophobic C-terminal segment that drives insertion into lipid membranes (32)(33)(34)(35)(36).…”

Length Effects in Antimicrobial Peptides of the (RW)nSeries

“…The guanidinium group of R has a more dispersed positive charge than the single amine of K, possibly enhancing electrostatic interactions between peptides and the negatively charged bacterial membrane surface (39,53). On the other hand, the bulkier W side chain may ensure more efficient interaction with membrane surfaces, allowing peptides to partition in the bilayer interface, in contrast with other nonpolar side chains such as F, P, or Y (46,56).…”