An extended surface of binding to Trk tyrosine kinase receptors in NGF and BDNF allows the engineering of a multifunctional pan-neurotrophin.
Neurotrophin-mediated cell survival and differentiation of vertebrate neurons is caused by ligand-specific binding to the Trk family of tyrosine kinase receptors. However, sites in the neurotrophins responsible for the binding to Trk receptors and the mechanisms whereby this interaction results in receptor activation and biological activity are unknown. Here we show that in nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), discontinuous stretches of amino acid residues group together on one side of the neurotrophin dimer forming a continuous surface responsible for binding to and activation of TrkA and TrkB receptors. Two symmetrical surfaces are formed along the two-fold axis of the neurotrophin dimer providing a model for ligand-mediated receptor dimerization. Mutated neurotrophins inducing similar levels of receptor phosphorylation showed different biological activities, suggesting that structural differences in a ligand may result in dissimilar responses in a given tyrosine kinase receptor. Our results allowed us to combine structural elements from NGF, BDNF and neurotrophin-3 to engineer a pan-neurotrophin that efficiently activates all Trk receptors and displays multiple neurotrophic specificities.
Department of Medical Chemistry, Karolinska Institute, Stockholm, Sweden.
C F
CF
Ibáñez
L L
LL
Ilag
J
J
Murray-Rust
H
H
Persson
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019208:Brain-Derived Neurotrophic Factor; D002478:Cells, Cultured; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D020933:Neurotrophin 3; D010766:Phosphorylation; D015202:Protein Engineering; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051381:Rats; D020801:Receptor, Ciliary Neurotrophic Factor; D020917:Receptor, trkA
D019208:Brain-Derived Neurotrophic Factor; D008565:Membrane Proteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020933:Neurotrophin 3; D011518:Proto-Oncogene Proteins; D020801:Receptor, Ciliary Neurotrophic Factor; D011505:Protein-Tyrosine Kinases; D020917:Receptor, trkA