title: Disorder in a target for the smad2 mad homology 2 domain and its implications for binding and specificity.
abstract: The Smad2 Mad homology 2 (MH2) domain binds to a diverse group of proteins which do not share a common sequence motif. We have used NMR to investigate the structure of one of these interacting proteins, the Smad binding domain (SBD) of Smad anchor for receptor activation (SARA). Our results indicate that the unbound SBD is highly disordered and forms no stable secondary or tertiary structures. Additionally we have used fluorescence binding studies to study the interaction between the MH2 domain and SBD and find that no region of the SBD dominates the interaction between the MH2 and the SBD. Our results are consistent with a series of hydrophobic patches on the MH2 that are able to recognize disordered regions of proteins. These findings elucidate a mechanism by which a single domain (MH2) can specifically recognize a diverse set of proteins which are unrelated by sequence, lead to a clearer picture of how MH2 domains function in the transforming growth factor-beta-signaling pathway and suggest possible mechanisms for controlling interactions with MH2 domains.
authors.affiliation: Department of Structural Biology and Biochemistry, Hospital for Sick Children, Toronto M5G 1X8, Canada.
authors.forename: P Andrew
authors.initials: PA
authors.lastname: Chong
authors.forename: Barish
authors.initials: B
authors.lastname: Ozdamar
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Wrana
authors.forename: Julie D
authors.initials: JD
authors.lastname: Forman-Kay
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D051899:Smad2 Protein; D015534:Trans-Activators / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; D020033:Protein Isoforms; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D005982:Glutathione Transferase; C116420:ZFYVE16 protein, human; D012697:Serine Endopeptidases