title: Regulatory R region of the CFTR chloride channel is a dynamic integrator of phospho-dependent intra- and intermolecular interactions.
abstract: Intrinsically disordered proteins play crucial roles in regulatory processes and often function as protein interaction hubs. Here, we present a detailed characterization of a full-length disordered hub protein region involved in multiple dynamic complexes. We performed NMR, CD, and fluorescence binding studies on the nonphosphorylated and highly PKA-phosphorylated human cystic fibrosis transmembrane conductance regulator (CFTR) regulatory region, a ∼200-residue disordered segment involved in phosphorylation-dependent regulation of channel trafficking and gating. Our data provide evidence for dynamic, phosphorylation-dependent, multisite interactions of various segments of the regulatory region for its intra- and intermolecular partners, including the CFTR nucleotide binding domains 1 and 2, a 42-residue peptide from the C terminus of CFTR, the SLC26A3 sulphate transporter and antisigma factor antagonist (STAS) domain, and 14-3-3β. Because of its large number of binding partners, multivalent binding of individually weak sites facilitates rapid exchange between free and bound states to allow the regulatory region to engage with different partners and generate a graded or rheostat-like response to phosphorylation. Our results enrich the understanding of how disordered binding segments interact with multiple targets. We present structural models consistent with our data that illustrate this dynamic aspect of phospho-regulation of CFTR by the disordered regulatory region.
authors.affiliation: Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Bozoky
authors.forename: Mickael
authors.initials: M
authors.lastname: Krzeminski
authors.forename: Ranjith
authors.initials: R
authors.lastname: Muhandiram
authors.forename: James R
authors.initials: JR
authors.lastname: Birtley
authors.forename: Ateeq
authors.initials: A
authors.lastname: Al-Zahrani
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Thomas
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Frizzell
authors.forename: Robert C
authors.initials: RC
authors.lastname: Ford
authors.forename: Julie D
authors.initials: JD
authors.lastname: Forman-Kay
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D001703:Biophysics; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism; D002942:Circular Dichroism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000378:metabolism*; D005453:Fluorescence; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D060066:Protein Interaction Maps / Q000235:genetics / Q000502:physiology*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics / Q000502:physiology*; D000076988:Sulfate Transporters
chemical_list: D048948:14-3-3 Proteins; D027963:Chloride-Bicarbonate Antiporters; C081011:SLC26A3 protein, human; D000076988:Sulfate Transporters; D019005:Cystic Fibrosis Transmembrane Conductance Regulator
keywords: fuzzy complex; protein interaction network