Amino Acid Determinants of beta-Hairpin Conformation in Erythropoeitin Receptor Agonist Peptides Derived from a Phage Display LibrarySkelton, N.J., Russell, S., de Sauvage, F., Cochran, A.G.
(2002) J.Mol.Biol. 316: 1121-1135
- PubMed: 11884148
- DOI: 10.1006/jmbi.2002.5410
- Primary Citation of Related Structures:
- PubMed Abstract:
- Identification of a 13 amino acid peptide mimetic of erythropoietin and description of amino acids critical for the mimetic activity of EMP1
Johnson, D.L.,Farrell, F.X.,Barbone, F.P.,McMahon, F.J.,Tullai, J.,Hoey, K.,Livnah, O.,Wrighton, N.C.,Middleton, S.A.,Loughney, D.A.,Dower, W.J.,Mulcahy, L.S.,Wilson, I.A.,Jolliffe, L.K.
(1998) Biochemistry 37: 3699
Display of peptide libraries on filamentous phage has led to the identification of peptides of the form X(2-5)CX(2)GPXTWXCX(2-5) (where X is a variable residue) that bind to the extra-cellular portion of the erythropoietin receptor (EPO-R). These pep ...
Display of peptide libraries on filamentous phage has led to the identification of peptides of the form X(2-5)CX(2)GPXTWXCX(2-5) (where X is a variable residue) that bind to the extra-cellular portion of the erythropoietin receptor (EPO-R). These peptides adopt beta-hairpin conformations when co-crystallized with EPO-R. Solution NMR studies reveal that the peptide is conformationally heterogeneous in the absence of receptor due to cis-trans isomerization about the Gly-Pro peptide bond. Replacement of the conserved threonine residue with glycine at the turn i+3 position produces a stable beta-hairpin conformation in solution, although this peptide no longer has activity in an EPO-R-dependent cell proliferation assay. A truncated form of the EPO-R-binding peptide (containing the i+3 glycine residue) also forms a highly populated, monomeric beta-hairpin. In contrast, phage-derived peptide antagonists of insulin-like growth factor binding protein 1 (IGFBP-1) have a high level of sequence identity with the truncated EPO-R peptide (eight of 12 residues) yet adopt a turn-alpha-helix conformation in solution. Peptides containing all possible pairwise amino acid substitutions between the EPO-R and IGFBP-1 peptides have been analyzed to assess the degree to which the non-conserved residues stabilize the hairpin or helix conformation. All four residues present in the original sequence are required for maximum population of either the beta-hairpin or alpha-helix conformation, although some substitutions have a more dominant effect. The results demonstrate that, within a given sequence, the observed conformation can be dictated by a small subset of the residues (in this case four out of 12).
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