title: Resonance assignments of the nucleotide-free wildtype MloK1 cyclic nucleotide-binding domain.
abstract: Cyclic nucleotide-sensitive ion channels, known as HCN and CNG channels play crucial roles in neuronal excitability and signal transduction of sensory cells. These channels are activated by binding of cyclic nucleotides to their intracellular cyclic nucleotide-binding domain (CNBD). A comparison of the structures of wildtype ligand-free and ligand-bound CNBD is essential to elucidate the mechanism underlying nucleotide-dependent activation of CNBDs. We recently reported the solution structure of the Mesorhizobium loti K1 (MloK1) channel CNBD in complex with cAMP. We have now extended these studies and achieved nearly complete assignments of (1)H, (13)C and (15)N resonances of the nucleotide-free CNBD. A completely new assignment of the nucleotide-free wildtype CNBD was necessary due to the sizable chemical shift differences as compared to the cAMP bound CNBD and the slow exchange behaviour between both forms. Scattering of these chemical shift differences over the complete CNBD suggests that nucleotide binding induces significant overall conformational changes.
authors.affiliation: Institut für Strukturbiologie und Biophysik, Strukturbiochemie (ISB-3), Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Schünke
authors.forename: Justin
authors.initials: J
authors.lastname: Lecher
authors.forename: Matthias
authors.initials: M
authors.lastname: Stoldt
authors.forename: U Benjamin
authors.initials: UB
authors.lastname: Kaupp
authors.forename: Dieter
authors.initials: D
authors.lastname: Willbold
mesh_terms: D054815:Cyclic Nucleotide-Gated Cation Channels / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009711:Nucleotides / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012231:Rhizobium / Q000378:metabolism*
chemical_list: D054815:Cyclic Nucleotide-Gated Cation Channels; D009711:Nucleotides