PDBsum entry 4r8c

Transport protein

PDB id: 4r8c

Contents

Protein chains

84 a.a.

92 a.a.

Ligands

MPD ×2

GLY ×10

Metals

_RB ×6

Waters ×27

PDB id:

4r8c

Name:

Transport protein

Title:

Crystal structure of cng mimicking nak-etpp mutant in complex with rb+

Structure:

Potassium channel protein. Chain: a, b. Fragment: residues 20-110. Engineered: yes. Mutation: yes

Source:

Bacillus cereus atcc 14579. Organism_taxid: 226900. Strain: atcc 14579 / dsm 31. Gene: bc_0669. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.50Å R-factor: 0.264 R-free: 0.257

Authors:

M.De March,L.M.R.Napolitano,S.Onesti

Key ref:

L.M.Napolitano et al. (2015). A structural, functional, and computational analysis suggests pore flexibility as the base for the poor selectivity of CNG channels. Proc Natl Acad Sci U S A, 112, E3619. PubMed id: 26100907 DOI: 10.1073/pnas.1503334112

Date:

01-Sep-14 Release date: 01-Jul-15

Protein chain

Q81HW2  (Q81HW2_BACCR) -  Potassium channel protein from Bacillus cereus (strain ATCC 14579 / DSM 31 / CCUG 7414 / JCM 2152 / NBRC 15305 / NCIMB 9373 / NCTC 2599 / NRRL B-3711)

Seq: 114 a.a.

Struc: 84 a.a.*

Protein chain

Q81HW2  (Q81HW2_BACCR) -  Potassium channel protein from Bacillus cereus (strain ATCC 14579 / DSM 31 / CCUG 7414 / JCM 2152 / NBRC 15305 / NCIMB 9373 / NCTC 2599 / NRRL B-3711)

Seq: 114 a.a.

Struc: 92 a.a.*

* PDB and UniProt seqs differ at 11 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B: E.C.?

DOI no: 10.1073/pnas.1503334112

Proc Natl Acad Sci U S A 112:E3619 (2015)

PubMed id: 26100907

A structural, functional, and computational analysis suggests pore flexibility as the base for the poor selectivity of CNG channels.

L.M.Napolitano, I.Bisha, M.De March, A.Marchesi, M.Arcangeletti, N.Demitri, M.Mazzolini, A.Rodriguez, A.Magistrato, S.Onesti, A.Laio, V.Torre.

ABSTRACT

Cyclic nucleotide-gated (CNG) ion channels, despite a significant homology with the highly selective K(+) channels, do not discriminate among monovalent alkali cations and are permeable also to several organic cations. We combined electrophysiology, molecular dynamics (MD) simulations, and X-ray crystallography to demonstrate that the pore of CNG channels is highly flexible. When a CNG mimic is crystallized in the presence of a variety of monovalent cations, including Na(+), Cs(+), and dimethylammonium (DMA(+)), the side chain of Glu66 in the selectivity filter shows multiple conformations and the diameter of the pore changes significantly. MD simulations indicate that Glu66 and the prolines in the outer vestibule undergo large fluctuations, which are modulated by the ionic species and the voltage. This flexibility underlies the coupling between gating and permeation and the poor ionic selectivity of CNG channels.