3K06

Crystal Structure of CNG mimicking NaK mutant, NaK-NTPP, K+ complex

Summary for 3K06

• Entry DOI: 10.2210/pdb3k06/pdb
• Related: 3K0G 3k03 3k04 3k08 3k0d
• Descriptor: Potassium channel protein NaK, (4S)-2-METHYL-2,4-PENTANEDIOL, POTASSIUM ION, ... (4 entities in total)
• Functional Keywords: nak-ntpp, ntpp, nak, cng mimicking, cng channel selectivity filter, nak-mutant, ionic channel, transport protein
• Biological source: Bacillus cereus
• Total number of polymer chains: 2
• Total formula weight: 22402.19

Authors

Jiang, Y.,Derebe, M.G. (deposition date: 2009-09-24, release date: 2011-01-12, Last modification date: 2024-02-21)

Primary citation

Derebe, M.G.,Zeng, W.,Li, Y.,Alam, A.,Jiang, Y.
Structural studies of ion permeation and Ca2+ blockage of a bacterial channel mimicking the cyclic nucleotide-gated channel pore.
Proc.Natl.Acad.Sci.USA, 108:592-597, 2011

PubMed Abstract: Cyclic nucleotide-gated (CNG) channels play an essential role in the visual and olfactory sensory systems and are ubiquitous in eukaryotes. Details of their underlying ion selectivity properties are still not fully understood and are a matter of debate in the absence of high-resolution structures. To reveal the structural mechanism of ion selectivity in CNG channels, particularly their Ca(2+) blockage property, we engineered a set of mimics of CNG channel pores for both structural and functional analysis. The mimics faithfully represent the CNG channels they are modeled after, permeate Na(+) and K(+) equally well, and exhibit the same Ca(2+) blockage and permeation properties. Their high-resolution structures reveal a hitherto unseen selectivity filter architecture comprising three contiguous ion binding sites in which Na(+) and K(+) bind with different ion-ligand geometries. Our structural analysis reveals that the conserved acidic residue in the filter is essential for Ca(2+) binding but not through direct ion chelation as in the currently accepted view. Furthermore, structural insight from our CNG mimics allows us to pinpoint equivalent interactions in CNG channels through structure-based mutagenesis that have previously not been predicted using NaK or K(+) channel models.

PubMed: 21187429
DOI: 10.1073/pnas.1013643108

Experimental method

X-RAY DIFFRACTION (1.58 Å)