Crystal structure of nerve growth factor in complex with the ligand-binding domain of the TrkA receptor

Abstract

Nerve growth factor (NGF) is involved in a variety of processes involving signalling, such as cell differentiation and survival, growth cessation and apoptosis of neurons. These events are mediated by NGF as a result of binding to its two cell-surface receptors, TrkA and p75. TrkA is a receptor with tyrosine kinase activity that forms a high-affinity binding site for NGF. Of the five domains comprising its extracellular portion, the immunoglobulin-like domain proximal to the membrane (TrkA-d5 domain) is necessary and sufficient for NGF binding. Here we present the crystal structure of human NGF in complex with human TrkA-d5 at 2.2 A resolution. The ligand-receptor interface consists of two patches of similar size. One patch involves the central beta-sheet that forms the core of the homodimeric NGF molecule and the loops at the carboxy-terminal pole of TrkA-d5. The second patch comprises the amino-terminal residues of NGF, which adopt a helical conformation upon complex formation, packing against the 'ABED' sheet of TrkA-d5. The structure is consistent with results from mutagenesis experiments for all neurotrophins, and indicates that the first patch may constitute a conserved binding motif for all family members, whereas the second patch is specific for the interaction between NGF and TrkA.

Selectivity of Cell Signaling in the Neuronal Response Based on NGF Mutations and Peptidomimetics in the Treatment of Alzheimers Disease

“…Scott et al, 1983;Walsh et al, 1999;Wiesmann et al, 1999;Yeo et al, 1997) . Sequence alignments of NGF, BDNF, and NT-3 (Ibanez et al, 1992;Ibanez et al, 1991;Ibanez et al, 1993;Ilag et al, 1994;Kullander & Ebendal, 1994;Kullander et al, 1997) demonstrate that each neurotrophin possesses seven variable regions that include the same residue positions.…”

“…Other substitution and deletion studies confirmed the importance of the N-terminus in specificity (Kullander et al, 1997;Woo et al, 1995;Kahle et al, 1992;Shih et al, 1994). Data from the crystal structure of human recombinant NGF complexed with the TrkA-d5 domains showed that the amino terminal residues 6-9, which were not well-defined in the original NGF crystal structure, adopted a helical conformation upon complex formation with their side chains almost completely buried in the interface (McDonald et al, 1991;Wiesmann et al, 1999) (Fig. 4).…”

“…Within the same region, H4, I6, and E11 participated in strong interactions with residues in the ABED TrkA -sheet. The authors labeled this region the specificity patch suggesting that the most important Trk receptor- (Wiesmann et al, 1999). Residues spanning the specificity patch, i.e.…”

“…A conceptual comparison to selectivity in other growth factor receptor systems, such as epidermal growth factor (EGF) and insulin, will also be made. (Ibanez et al, 1991;Ibanez et al, 1993;Ilag et al, 1994) are equivalent to loops 1, 2, and 4 (L1, L2, L4) defined in the structure (Wiesmann et al, 1999).…”

Designing allosteric peptide ligands targeting a globular protein

“…Both of these regions of have been suggested as sites involved in NGF binding based on the X-ray crystal structure of human NGF complexed with human TrkA. 21,22 Targeting Accessible Peptide Segments of a Non-Membrane-Involved Globular Protein…”