Structural basis of Smad2 recognition by the Smad anchor for receptor activation

Science. 2000 Jan 7;287(5450):92-7. doi: 10.1126/science.287.5450.92.

Abstract

The Smad proteins mediate transforming growth factor-beta (TGFbeta) signaling from the transmembrane serine-threonine receptor kinases to the nucleus. The Smad anchor for receptor activation (SARA) recruits Smad2 to the TGFbeta receptors for phosphorylation. The crystal structure of a Smad2 MH2 domain in complex with the Smad-binding domain (SBD) of SARA has been determined at 2.2 angstrom resolution. SARA SBD, in an extended conformation comprising a rigid coil, an alpha helix, and a beta strand, interacts with the beta sheet and the three-helix bundle of Smad2. Recognition between the SARA rigid coil and the Smad2 beta sheet is essential for specificity, whereas interactions between the SARA beta strand and the Smad2 three-helix bundle contribute significantly to binding affinity. Comparison of the structures between Smad2 and a comediator Smad suggests a model for how receptor-regulated Smads are recognized by the type I receptors.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Activin Receptors, Type I*
  • Amino Acid Sequence
  • Binding Sites
  • Carrier Proteins / chemistry*
  • Carrier Proteins / metabolism*
  • Crystallography, X-Ray
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Hydrogen Bonding
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation
  • Point Mutation
  • Protein Conformation
  • Protein Serine-Threonine Kinases / chemistry
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Receptor, Transforming Growth Factor-beta Type I
  • Receptors, Transforming Growth Factor beta / chemistry
  • Receptors, Transforming Growth Factor beta / genetics
  • Receptors, Transforming Growth Factor beta / metabolism
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction
  • Smad2 Protein
  • Trans-Activators / chemistry*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Zinc Fingers

Substances

  • Carrier Proteins
  • DNA-Binding Proteins
  • Receptors, Transforming Growth Factor beta
  • Recombinant Fusion Proteins
  • Smad2 Protein
  • Trans-Activators
  • Protein Serine-Threonine Kinases
  • Activin Receptors, Type I
  • Receptor, Transforming Growth Factor-beta Type I

Associated data

  • PDB/1DEV