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This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: fj.08-113142v1 fj.08-113142v2 22/12/4338    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Coutant, J. Articles by Bomsel, M. Search for Related Content PubMed PubMed Citation Articles by Coutant, J. Articles by Bomsel, M.

Both lipid environment and pH are critical for determining physiological solution structure of 3-D-conserved epitopes of the HIV-1 gp41-MPER peptide P1

Jérôme Coutant^*,1, Huifeng Yu^,,1, Marie-Jeanne Clément^*, Annette Alfsen^,, Flavio Toma^*,2, Patrick A. Curmi^*,2 and Morgane Bomsel^,,2

^* Structure Activité des Biomolécules Normales et Pathologiques, INSERM/UEVE U829 Université d’Evry, Evry, France;

Entrée Muqueuse du VIH et Immunité Muqueuse, Département de Biologie Cellulaire, Institut Cochin, Université Paris Descartes, CNRS UMR 8104, Paris, France; and

INSERM U567, Paris, France

²Correspondence: M.B., Entrée Muqueuse du VIH et Immunité Muqueuse, Département de Biologie Cellulaire, Institut Cochin, Université Paris Descartes, CNRS UMR 8104, 22 rue Méchain, 75014 Paris, France. E-mail: morgane.bomsel{at}inserm.fr; F.T. and P.A.C., Structure Activité des Biomolécules Normales et Pathologiques, INSERM/UEVE U829 Université d’Evry, Bât. Maupertuis, rue du Père Jarlan, 91025 Evry, France. E-mail: F.T., flavio.toma{at}univ-evry.fr; P.A.C., pcurmi{at}univ-evry.fr

In terms of background, the solution structure of monomeric peptide P1 (residues 649–683), located in the conserved membrane proximal region (MPER) of HIV-1 envelope glycoprotein gp41, is first reported here in dodecylphosphocholine (DPC) micelles. P1 is the minimal MPER region that permits interaction with the mucosal galactosyl ceramide HIV-receptor; it also contains epitopes recognized by major gp41-specific, broadly neutralizing immunoglobulin Gs (IgGs), 2F5 and 4E10, determinant in HIV fusion/infection. Our principal findings were as follows: the structural stability of P1 is pH dependent, as the -helix comprising Q653 I682, present at pH 3.3, is destabilized at higher pH values. At pH 6, the E-rich N-terminal half of P1 (residues 650–666), partially overlapping the 2F5-specific epitope, becomes fully disordered, while the W-rich C-terminal half conserves two shorter helices (W666–W670 and W672–W680), separated by a well-defined bend overlapped by the 4E10-specific epitope. The two IgGs bind to P1 on DPC micelles with binding parameters (K_d) in the nanomolar range. Next, P1 was derivatized with phosphatidylethanolamine at its C terminal and inserted into liposomes of varied lipid composition, thereby enabling P1 to move laterally. Alternatively, an infectious virus-binding assay was established. The K_d of both 2F5 and 4E10 IgGs measured on viral liposome and virus are similar and much lower than for the binding of the free peptide. In conclusion, P1, in a lipid environment, is an optimized MPER-derived peptide suitable for designing an immunogen inducing broadly neutralizing antibodies to HIV.—Coutant, J., Yu, H., Clément, M.-J., Alfsen, A., Toma, F., Curmi, P. A., Bomsel, M. Both lipid environment and pH are critical for determining physiological solution structure of 3-D-conserved epitopes of the HIV-1 gp41-MPER peptide P1.

Key Words: 2F5 IgG • 4E10 IgG • glycosphingolipid • mucosa • HIV envelope glycoprotein • NMR