title: Structure of a Numb PTB domain-peptide complex suggests a basis for diverse binding specificity.
abstract: The phosphotyrosine-binding (PTB) domain of Numb, a protein involved in asymmetric cell division, has recently been shown to bind to the adapter protein Lnx through an LDNPAY sequence, to the Numb-associated kinase (Nak) through a sequence that does not contain an NPXY motif and to GP(p)Y-containing peptides obtained from library screening. We show here that these diverse peptide sequences bind with comparable affinities to the Numb PTB domain at a common binding site on the surface of the protein. The NMR structure of the Numb PTB domain in complex with a GPpY-containing peptide reveals a novel mechanism of binding with the peptide in a helical turn that does not hydrogen bond to the PTB domain beta-sheet. These results suggest that PTB domains can potentially have multiple modes of peptide recognition and provide a structural basis from which the multiple functions of the Numb PTB domain during asymmetric cell division could arise.
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada.
authors.forename: S C
authors.initials: SC
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Zwahlen
authors.forename: S J
authors.initials: SJ
authors.lastname: Vincent
authors.forename: C J
authors.initials: CJ
authors.lastname: McGlade
authors.forename: L E
authors.initials: LE
authors.lastname: Kay
authors.forename: T
authors.initials: T
authors.lastname: Pawson
authors.forename: J D
authors.initials: JD
authors.lastname: Forman-Kay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D002455:Cell Division; D004330:Drosophila; D029721:Drosophila Proteins; D006860:Hydrogen Bonding; D007605:Juvenile Hormones / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism*; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017433:Protein Structure, Secondary
chemical_list: D002352:Carrier Proteins; D029721:Drosophila Proteins; D007605:Juvenile Hormones; D010446:Peptide Fragments; C060606:numb protein, Drosophila; D019000:Phosphotyrosine; C109770:Nak protein, Drosophila; D017346:Protein Serine-Threonine Kinases