Crystallization and preliminary diffraction analysis of the CAL PDZ domain in complex with a selective peptide inhibitor

• Published in: Acta crystallographica. Section F, Structural biology and crystallization communications Structural biology and crystallization communications, 2011-05, Vol.67 (5), p.600-603
• Main Authors: Amacher, Jeanine F., Cushing, Patrick R., Weiner, Joshua A., Madden, Dean R.
• Format: Article
• Language: English
• Subjects: 3C Viral Proteases; 60 APPLIED LIFE SCIENCES; Adaptor Proteins, Signal Transducing; BASIC BIOLOGICAL SCIENCES; Carrier Proteins - chemistry; CFTR-associated ligand; Chlorides; CHROMATOGRAPHY; Coefficients; CRYSTALLIZATION; Crystallization Communications; Crystallography, X-Ray; Crystals; Cysteine Endopeptidases - chemistry; cystic fibrosis; DIFFRACTION; FIBROSIS; Golgi Matrix Proteins; HOMEOSTASIS; Homogeneity; Inhibitors; Membrane Proteins - chemistry; Membrane Transport Proteins; metal-affinity chromatography; MUTANTS; MUTATIONS; PDZ-peptide binding; Peptide Fragments - chemistry; PEPTIDES; PROTEINS; PURIFICATION; recombinant expression; RESOLUTION; Rhinovirus - enzymology; SPACE GROUPS; TARGETS; Viral Proteins - chemistry
• ISSN: 1744-3091; 1744-3091; 2053-230X
• DOI: 10.1107/S1744309111009985

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 P212121, 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 Å3 Da−1), it appears that the asymmetric unit contains two complexes.