Uniform TitleTemplate-assembled peptide models of the N-peptide helix bundle from HIV-1 Gp41
NameXu, Weiming (author), Taylor, John (chair), Romsted, Laurence (internal member), Warmuth, Ralf (internal member), Lobel, Peter (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectChemistry and Chemical Biology,
DescriptionThe HIV-1 pandemic is one of the most serious health problems facing the world today. Infection of target cells by HIV-1 is initiated by fusion of viral and cell membranes, which is mediated by the viral glycoproteins, gp120 and gp41. After initial cell binding by gp120, the folding of gp41 to form a stable six-helix bundle structure is directly associated with membrane fusion. This helix bundle is composed of an α-helical trimer of gp41 N-helices, with three copies of the α-helical gp41 C-peptides folded onto it in an antiparallel orientation. Peptides that interfere with the formation of this six-helix bundle structure by targeting either the N-helix or the C-helix are believed to be able to block the cell fusion process and therefore prevent HIV-1 infection.
In this study, we successfully synthesized three-helix peptide structures of gp41 as models of the internal N-helix bundle, by assembling three copies of N-peptides onto three-fold symmetric templates. The templates were derived from cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid (Kemp's Triacid, KTA) or tris(2-aminoethyl)amine (TREN), which represent choices of rigid and flexible molecules, respectively, for organization of the folding of the N-peptide three-helix bundle.
Biophysical analysis of the four synthetic model structures, KTA-3N29, TREN-3N29, KTA-3N29b and TREN-3K-N29b, demonstrated that, at neutral pH, they all exist as monomers with high helix contents. Binding isotherms, measured by circular dichroism spectropolarimetry in the presence of physiological salt, indicated that KTA-3N29b binds three copies of the C-peptide native sequence, with a KD of about 260 nM, while TREN-3K-N29b binds to C-peptide with a KD in the low-micromolar range. Within the scope of this investigation, KTA-Br, the relatively more rigid template derived from KTA, was the best design for a template for the N-peptide bundle, since it generated the most helical, and most stable three-helix bundle structure with the highest binding affinity for C-peptides. These features of KTA-3N29b demonstrate that this templated three-helix bundle serves as a functional model for the native N-peptide structure that will allow detailed studies of the folding and thermodynamic stability of the gp41 six-helix bundle, and may aid the future development of potent HIV-1 fusion inhibitors and immunogens.
NoteIncludes bibliographical references.
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.