title: Solution structure of the chick TGFbeta type II receptor ligand-binding domain.
abstract: The transforming growth factor beta (TGFbeta) signaling pathway influences cell proliferation, immune responses, and extracellular matrix reorganization throughout the vertebrate life cycle. The signaling cascade is initiated by ligand-binding to its cognate type II receptor. Here, we present the structure of the chick type II TGFbeta receptor determined by solution NMR methods. Distance and angular constraints were derived from 15N and 13C edited NMR experiments. Torsion angle dynamics was used throughout the structure calculations and refinement. The 20 final structures were energy minimized using the generalized Born solvent model. For these 20 structures, the average backbone root-mean-square distance from the average structure is below 0.6A. The overall fold of this 109-residue domain is conserved within the superfamily of these receptors. Chick receptors fully recognize and respond to human TGFbeta ligands despite only 60% identity at the sequence level. Comparison with the human TGFbeta receptor determined by X-ray crystallography reveals different conformations in several regions. Sequence divergence and crystal packing interactions under low pH conditions are likely causes. This solution structure identifies regions were structural changes, however subtle, may occur upon ligand-binding. We also identified two very well conserved molecular surfaces. One was found to bind ligand in the crystallized human TGFbeta3:TGFbeta type II receptor complex. The other, newly identified area can be the interaction site with type I and/or type III receptors of the TGFbeta signaling complex.
authors.affiliation: Department of Biological Sciences, 465 21st Avenue South, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Marlow
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Brown
authors.forename: Joey V
authors.initials: JV
authors.lastname: Barnett
authors.forename: Andrzej M
authors.initials: AM
authors.lastname: Krezel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D008024:Ligands; D018125:Receptors, Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II