title: Association of the cystic fibrosis transmembrane regulator with CAL: structural features and molecular dynamics.
abstract: The association of the cystic fibrosis transmembrane regulator (CFTR) with two PDZ-containing molecular scaffolds (CAL and EBP50) plays an important role in CFTR trafficking and membrane maintenance. The CFTR-molecular scaffold interaction is mediated by the association of the C-terminus of the transmembrane regulator with the PDZ domains. Here, we characterize the structure and dynamics of the PDZ of CAL and the complex formed with CFTR employing high-resolution NMR. On the basis of NMR relaxation data, the alpha2 helix as well as the beta2-beta3 loop of CAL PDZ domain undergoes rapid dynamics. Molecular dynamics simulations suggest a concerted motion between the alpha2 helix and the beta1-beta2 and beta2-beta3 loops, elements which define the binding pocket, suggesting that dynamics may play a role in PDZ-ligand specificity. The C-terminus of CFTR binds to CAL with the final four residues (-D(-)(3)-T-R-L(0)) within the canonical PDZ-binding motif, between the beta2 strand and the alpha2 helix. The R(-)(1) and D(-)(3) side chains make a number of contacts with the PDZ domain; many of these interactions differ from those in the CFTR-EBP50 complex, suggesting sites that can be targeted in the development of PDZ-selective inhibitors that may help modulate CFTR function.
authors.affiliation: Department of Molecular Pharmacology, Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Piserchio
authors.forename: Abigail
authors.initials: A
authors.lastname: Fellows
authors.forename: Dean R
authors.initials: DR
authors.lastname: Madden
authors.forename: Dale F
authors.initials: DF
authors.lastname: Mierke
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000077614:Golgi Matrix Proteins; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D017434:Protein Structure, Tertiary
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C434484:GOPC protein, human; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator