title: The cystic fibrosis-causing mutation deltaF508 affects multiple steps in cystic fibrosis transmembrane conductance regulator biogenesis.
abstract: The deletion of phenylalanine 508 in the first nucleotide binding domain of the cystic fibrosis transmembrane conductance regulator is directly associated with >90% of cystic fibrosis cases. This mutant protein fails to traffic out of the endoplasmic reticulum and is subsequently degraded by the proteasome. The effects of this mutation may be partially reversed by the application of exogenous osmolytes, expression at low temperature, and the introduction of second site suppressor mutations. However, the specific steps of folding and assembly of full-length cystic fibrosis transmembrane conductance regulator (CFTR) directly altered by the disease-causing mutation are unclear. To elucidate the effects of the ΔF508 mutation, on various steps in CFTR folding, a series of misfolding and suppressor mutations in the nucleotide binding and transmembrane domains were evaluated for effects on the folding and maturation of the protein. The results indicate that the isolated NBD1 responds to both the ΔF508 mutation and intradomain suppressors of this mutation. In addition, identification of a novel second site suppressor of the defect within the second transmembrane domain suggests that ΔF508 also effects interdomain interactions critical for later steps in the biosynthesis of CFTR.
authors.affiliation: Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Thibodeau
authors.forename: John M
authors.initials: JM
authors.lastname: Richardson
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Linda
authors.initials: L
authors.lastname: Millen
authors.forename: Jarod
authors.initials: J
authors.lastname: Watson
authors.forename: Juan L
authors.initials: JL
authors.lastname: Mendoza
authors.forename: Kai
authors.initials: K
authors.lastname: Du
authors.forename: Sharon
authors.initials: S
authors.lastname: Fischman
authors.forename: Hanoch
authors.initials: H
authors.lastname: Senderowitz
authors.forename: Gergely L
authors.initials: GL
authors.lastname: Lukacs
authors.forename: Kevin
authors.initials: K
authors.lastname: Kirk
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Thomas
mesh_terms: D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017384:Sequence Deletion; D013489:Suppression, Genetic
chemical_list: D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D010649:Phenylalanine