Structural Insights into Ion Selectivity and Calcium Blockage in Cyclic Nucleotide Gated Channels

Cyclic nucleotides-gated (CNG) channels play an essential role in the visual and olfactory sensory systems and are ubiquitously expressed in a variety of neuronal and non neuronal cells. Details of their underlying ion selectivity properties are still not fully understood and a matter of debate in the absence of high resolution structures. Presented in this study are high resolution (1.58-1.95Å) crystal structures and functional analyses of engineered mimics of CNG channels by duplicating their selectivity filter sequences in the background of the bacterial non-selective NaK channel. Mimics share several striking functional similarities in ion selectivity with eukaryotic CNG channels: they are non-selective and permeate Na+ and K+ equally well; externally added Ca2+ serves as a permeating blocker, with the conserved acidic residue in the filter mediating Ca2+ binding. Structures reveal a hitherto unseen selectivity filter architecture that suggests that CNG channel selectivity filters likely comprise three contiguous ion binding sites. The high resolution structures also allow for a thorough characterization of monovalent and divalent ion permeation which, in combination with electrophysiological recordings, offers structural insight into CNG channel function at an unprecedented level of detail.

Author dc:creator

• Derebe, Mehabaw Getahun

Contributors dc:contributor

• Jiang, Youxing

• Ion Channel Gating
• Sensory Functions
• Recombinant Proteins

Language dc:language

en

Identifier

795781252

OAI identifier oai:identifier

oai:utswmed-ir.tdl.org:2152.5/727