Peter H. Jensen

Structural Basis for a Direct Interaction between FGFR1 and NCAM and Evidence for a Regulatory Role of ATP

The neural cell adhesion molecule (NCAM) promotes axonal outgrowth, presumably through an interaction with the fibroblast growth factor receptor (FGFR). NCAM also has a little-understood ATPase activity. We here demonstrate for the first time a direct interaction between NCAM (fibronectin type III [F3] modules 1 and 2) and FGFR1 (Ig modules 2 and 3) by surface plasmon resonance (SPR) analysis. The structure of the NCAM F3 module 2 was determined by NMR and the module was shown by NMR to interact with the FGFR1 Ig module 3 and ATP. The NCAM sites binding to FGFR and ATP were found to overlap and ATP was shown by SPR to inhibit the NCAM-FGFR binding, indicating that ATP probably regulates the NCAM-FGFR interaction. Furthermore, we demonstrate that the NCAM module was able to induce activation (phosphorylation) of FGFR and to stimulate neurite outgrowth. In contrast, ATP inhibited neurite outgrowth induced by the module.

Identification of a neuritogenic ligand of the neural cell adhesion molecule using a combinatorial library of synthetic peptides

The neural cell adhesion molecule (NCAM) plays a key role in neural development, regeneration, and learning. In this study, we identified a synthetic peptide-ligand of the NCAM Ig1 module by combinatorial chemistry and showed it could modulate NCAM-mediated cell adhesion and signal transduction with high potency. In cultures of dissociated neurons, this peptide, termed C3, stimulated neurite outgrowth by activating a signaling pathway identical to that activated by homophilic NCAM binding. A similar effect was shown for the NCAM Ig2 module, the endogenous ligand of NCAM Ig1. By nuclear magnetic resonance spectroscopy, the C3 binding site in the NCAM Ig1 module was mapped and shown to be different from the binding site of the NCAM Ig2 module. The C3 peptide may prove useful as a lead in development of therapies for neurodegenerative disorders, and the C3 binding site of NCAM Ig1 may represent a target for discovery of nonpeptide drugs.

Structure and interactions of NCAM modules 1 and 2, basic elements in neural cell adhesion

The structure in solution of the second Ig-module fragment of residues 117–208 of NCAM has been determined. Like the first Ig-module of residues 20–116, it belongs to the I set of the immunogloblin superfamily. Module 1 and module 2 interact weakly, and the binding sites of this interaction have been identified. The two–module fragment NCAM(20–208) is a stable dimer. Removal of the charged residues in these sites in NCAM(20–208) abolishes the dimerization. Modeling the dimer of NCAM(20–208) to fit the interactions of these charges produces one coherent binding site for the formation of two antiparallel strands of the first two NCAM modules. This mode of binding could be a major element in trans–cellular interactions in neural cell adhesion.

Different secondary structure elements as scaffolds for protein folding transition states of two homologous four-helix bundles.

Comparison of the folding processes for homologue proteins can provide valuable information about details in the interactions leading to the formation of the folding transition state. Here the folding kinetics of 18 variants of yACBP and 3 variants of bACBP have been studied by Φ‐value analysis. In combination with Φ‐values from previous work, detailed insight into the transition states for folding of both yACBP and bACBP has been obtained. Of the 16 sequence positions that have been studied in both yACBP and bACBP, 5 (V12, I/L27, Y73, V77, and L80) have high Φ‐values and appear to be important for the transition state formation in both homologues. Y31, A34, and A69 have high Φ‐values only in yACBP, while F5, A9, and I74 have high Φ‐values only in bACBP. Thus, additional interactions between helices A2 and A4 appear to be important for the transition state of yACBP, whereas additional interactions between helices A1 and A4 appear to be important for the transition state of bACBP. To examine whether these differences could be assigned to different packing of the residues in the native state, a solution structure of yACBP was determined by NMR. Small changes in the packing of the hydrophobic side‐chains, which strengthen the interactions between helices A2 and A4, are observed in yACBP relative to bACBP. It is suggested that different structure elements serve as scaffolds for the folding of the 2 ACBP homologues. Proteins 2005.

Erratum: Erratum to 'Identification of a neuritogenic ligand of the neural cell adhesion molecule using a combinatorial library of synthetic peptides”

On p. 1000 of the October 1999 issue, “Identification of a neuritogenic ligand of the neural cell adhesion molecule using a combinatorial library of synthetic peptides” by Lars C.B. Rønn, Marianne Olsen, Søren Østergaard, Vladislav Kiselyov, Vladimir Berezin, Marie T. Mortensen, Mathilde H. Lerche, Peter H. Jensen, Vladislav Soroka, Jane L. Saffell, Patrick Doherty, Flemming M. Poulsen, Elisabeth Bock, and Arne Holm, author Jane Saffells name was misspelled.