title: Crystallization and preliminary diffraction analysis of the CAL PDZ domain in complex with a selective peptide inhibitor.
abstract: Cystic fibrosis (CF) is associated with loss-of-function mutations in the CF transmembrane conductance regulator (CFTR), which regulates epithelial fluid and ion homeostasis. The CFTR cytoplasmic C-terminus interacts with a number of PDZ (PSD-95/Dlg/ZO-1) proteins that modulate its intracellular trafficking and chloride-channel activity. Among these, the CFTR-associated ligand (CAL) has a negative effect on apical-membrane expression levels of the most common disease-associated mutant ΔF508-CFTR, making CAL a candidate target for the treatment of CF. A selective peptide inhibitor of the CAL PDZ domain (iCAL36) has recently been developed and shown to stabilize apical expression of ΔF508-CFTR, enhancing net chloride-channel activity, both alone and in combination with the folding corrector corr-4a. As a basis for structural studies of the CAL-iCAL36 interaction, a purification protocol has been developed that increases the oligomeric homogeneity of the protein. Here, the cocrystallization of the complex in space group P2(1)2(1)2(1), with unit-cell parameters a = 35.9, b = 47.7, c = 97.3 Å, is reported. The crystals diffracted to 1.4 Å resolution. Based on the calculated Matthews coefficient (1.96 Å(3) Da(-1)), it appears that the asymmetric unit contains two complexes.
authors.affiliation: Department of Biochemistry, Dartmouth Medical School, 7200 Vail Building, Hanover, NH 03755, USA.
authors.forename: Jeanine F
authors.initials: JF
authors.lastname: Amacher
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Cushing
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Weiner
authors.forename: Dean R
authors.initials: DR
authors.lastname: Madden
mesh_terms: D000086042:3C Viral Proteases; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases / Q000737:chemistry; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins / Q000737:chemistry*; D026901:Membrane Transport Proteins; D010446:Peptide Fragments / Q000737:chemistry*; D012229:Rhinovirus / Q000201:enzymology; D014764:Viral Proteins / Q000737:chemistry
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; D010446:Peptide Fragments; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases