Reorientation of the helix of the tryptophan-rich gp41W peptide from HIV-1 at interfaces

Abstract

The glycoprotein gp41 from the Human Immunodeficiency Virus type 1 (HIV-1) has an amino acid sequence enriched in tryptophan residues, the so-called gp41W peptide (i.e., KWASLWNWFNITNWLWYIK) and plays a crucial role in HIV-1 host cell infection. Using the coupling of Second Harmonic Generation targeting the tryptophan residues with lateral surface tension measurements, we investigate the interaction of gp41W with a neat air∕water and a lipid∕water interfaces. At the air∕water interface, gp41W presents a well-defined orientation and this orientation is strongly modified at the lipid∕water interface, depending on the surface pressure. These results show that this strategy is well suited to monitor tryptophan containing α-helices orientation at lipid∕water interfaces.

Ordering and Nonideality of Air–Ionic Liquid Interfaces in Surface Second Harmonic Generation

“…We used first the p-in and P-out polarization configuration (also named the pP SHG intensity) yielding the largest SHG intensities. 38 The SHG intensity for the 45S configuration, e.g., the maximum intensity for the S-out configuration obtained for a γ = 45°input polarization angle, was also recorded for the Table 1. Refractive Indices at Optical Frequencies ω and 2ω for the Different ILs a n 2ω (400 nm)…”

“…The SHG intensities from the different interfaces were then collected for two configurations. We used first the p-in and P-out polarization configuration (also named the pP SHG intensity) yielding the largest SHG intensities . The SHG intensity for the 45S configuration, e.g., the maximum intensity for the S-out configuration obtained for a γ = 45° input polarization angle, was also recorded for the different ILs .…”

Unique Vibrational Features as a Direct Probe of Specific Antigen–Antibody Recognition at the Surface of a Solid‐Supported Hybrid Lipid Bilayer

“…More specifically, second‐order NLO techniques have set one′s heart on biological interfaces for multiple reasons, first of all the possibility to univocally probe those nano‐bio‐interfaces while surrounded by a macroscopic liquid environment, with the unique advantage that the latter does not contribute to the signal . For example, lipid mono‐ or bilayers mimicking cell membranes are still extensively investigated in interaction with peptides or membrane proteins . In addition to fundamental research purposes, second‐order NLO spectroscopies have provided successful proofs in detecting biological recognition in nanoscale devices.…”

“…[9,10,11] For example, lipid mono-or bilayers mimicking cell membranes are still extensively investigated in interaction with peptides or membrane proteins. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] In addition to fundamental research purposes, second-order NLO spectroscopies have provided successful proofs in detecting biological recognition in nanoscale devices. Second harmonic generation (SHG) ands um frequency generation (SFG) probe the electronic and vibrational responses, respectively,o f interfacial systems.…”