PDBsum entry 1kvf

De novo protein

PDB id: 1kvf

Contents

Protein chain

17 a.a.

PDB id:

1kvf

Name:

De novo protein

Title:

Emp-18 erythropoietin receptor agonist peptide

Structure:

Protein: emp-18 receptor agonist. Chain: a. Engineered: yes

Source:

Synthetic: yes. Other_details: the peptide was chemically synthesized. It is a novel sequence derived from phage-display selection.

NMR struc:

20 models

Authors:

N.J.Skelton,S.Russell,F.De Sauvage,A.G.Cochran

Key ref:

N.J.Skelton et al. (2002). Amino acid determinants of beta-hairpin conformation in erythropoeitin receptor agonist peptides derived from a phage display library. J Mol Biol, 316, 1111-1125. PubMed id: 11884148 DOI: 10.1006/jmbi.2002.5410

Date:

25-Jan-02 Release date: 06-Mar-02

Protein chain

No UniProt id for this chain

Struc: 17 a.a.

DOI no: 10.1006/jmbi.2002.5410

J Mol Biol 316:1111-1125 (2002)

PubMed id: 11884148

Amino acid determinants of beta-hairpin conformation in erythropoeitin receptor agonist peptides derived from a phage display library.

N.J.Skelton, S.Russell, F.de Sauvage, A.G.Cochran.

ABSTRACT

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).

Selected figure(s)

Figure 6.
Figure 6. Comparison of the crystal structure of EPO-R-bound EMP-1 with EMP-18b and EPO-3 in solution. The minimized mean structures of EMP-18b (green) and EPO-3 (cyan) were superimposed on the crystal structure (pink; PDB accession code 1ebp chain D) using the N, C^a and C atoms of residues Cys2-Phe4 and Trp9 to Cys11 (EPO-3 numbering). The C^a of the residues corresponding to Phe4 and Trp9 of EPO-3 are shown as spheres, and the carbonyl oxygen atoms of the turn residues are colored red. The EPO-R atoms that donate a hydrogen bond to the peptide EMP-1 in the complex are indicated.

Figure 8.
Figure 8. Structural comparison of EPO-3 and EPO-4. (a) Minimized mean structure of EPO-3. For the case of Phe4 and Trp9, two representative side-chain conformations from the ensemble are depicted (see the text). (b) Minimized mean structure of EPO-4. For clarity, the side-chain atoms of Ser1 and Lys12 are omitted.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2002, 316, 1111-1125) copyright 2002.

Figures were selected by an automated process.