title: Structure of calmodulin complexed with an olfactory CNG channel fragment and role of the central linker: residual dipolar couplings to evaluate calmodulin binding modes outside the kinase family.
abstract: The NMR high-resolution structure of calmodulin complexed with a fragment of the olfactory cyclic-nucleotide gated channel is described. This structure shows features that are unique for this complex, including an active role of the linker connecting the N- and C-lobes of calmodulin upon binding of the peptide. Such linker is not only involved in the formation of an hydrophobic pocket to accommodate a bulky peptide residue, but it also provides a positively charged region complementary to a negative charge of the target. This complex of calmodulin with a target not belonging to the kinase family was used to test the residual dipolar coupling (RDC) approach for the determination of calmodulin binding modes to peptides. Although the complex here characterized belongs to the (1--14) family, high Q values were obtained with all the 1:1 complexes for which crystalline structures are available. Reduction of the RDC data set used for the correlation analysis to structured regions of the complex allowed a clear identification of the binding mode. Excluded regions comprise calcium binding loops and loops connecting the EF-hand motifs.
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, via della Ricerca Scientifica, 00133, Rome, Italy.
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: Contessa
authors.forename: Maria
authors.initials: M
authors.lastname: Orsale
authors.forename: Sonia
authors.initials: S
authors.lastname: Melino
authors.forename: Vincent
authors.initials: V
authors.lastname: Torre
authors.forename: Maurizio
authors.initials: M
authors.lastname: Paci
authors.forename: Alessandro
authors.initials: A
authors.lastname: Desideri
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Cicero
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D024342:Amino Acids, Acidic / Q000737:chemistry; D024322:Amino Acids, Aromatic / Q000737:chemistry; D024361:Amino Acids, Basic / Q000737:chemistry; D000818:Animals; D001665:Binding Sites; D002147:Calmodulin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054815:Cyclic Nucleotide-Gated Cation Channels; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009590:Nitrogen Radioisotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D009830:Olfactory Bulb / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism*; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D015203:Reproducibility of Results; D017386:Sequence Homology, Amino Acid; D013059:Spectrum Analysis, Raman; D014982:Xenopus laevis
chemical_list: D024342:Amino Acids, Acidic; D024322:Amino Acids, Aromatic; D024361:Amino Acids, Basic; D002147:Calmodulin; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D009590:Nitrogen Radioisotopes; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D011494:Protein Kinases