PDBsum entry 2zd9

Membrane protein

PDB id: 2zd9

Contents

Protein chains

223 a.a. *

Metals

__K ×5

* Residue conservation analysis

PDB id:

2zd9

Name:

Membrane protein

Title:

Structure of a bacterial cyclic-nucleotide regulated ion channel

Structure:

Mll3241 protein. Chain: a, b, c, d. Engineered: yes

Source:

Mesorhizobium loti. Organism_taxid: 381. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

4.00Å R-factor: 0.308 R-free: 0.333

Authors:

G.M.Clayton,J.M.Cabral-Morais

Key ref:

G.M.Clayton et al. (2008). Structure of the transmembrane regions of a bacterial cyclic nucleotide-regulated channel. Proc Natl Acad Sci U S A, 105, 1511-1515. PubMed id: 18216238 DOI: 10.1073/pnas.0711533105

Date:

21-Nov-07 Release date: 02-Dec-08

Protein chains

Q98GN8  (CNGK1_RHILO) -  Cyclic nucleotide-gated potassium channel mll3241 from Mesorhizobium japonicum (strain LMG 29417 / CECT 9101 / MAFF 303099)

Seq: 355 a.a.

Struc: 223 a.a.

DOI no: 10.1073/pnas.0711533105

Proc Natl Acad Sci U S A 105:1511-1515 (2008)

PubMed id: 18216238

Structure of the transmembrane regions of a bacterial cyclic nucleotide-regulated channel.

G.M.Clayton, S.Altieri, L.Heginbotham, V.M.Unger, J.H.Morais-Cabral.

ABSTRACT

The six-transmembrane helix (6 TM) tetrameric cation channels form the largest ion channel family, some members of which are voltage-gated and others are not. There are no reported channel structures to match the wealth of functional data on the non-voltage-gated members. We determined the structure of the transmembrane regions of the bacterial cyclic nucleotide-regulated channel MlotiK1, a non-voltage-gated 6 TM channel. The structure showed how the S1-S4 domain and its associated linker can serve as a clamp to constrain the gate of the pore and possibly function in concert with ligand-binding domains to regulate the opening of the pore. The structure also led us to hypothesize a new mechanism by which motions of the S6 inner helices can gate the ion conduction pathway at a position along the pore closer to the selectivity filter than the canonical helix bundle crossing.

Selected figure(s)

Figure 1.
Architecture of 6 TM channel. (A) Illustration of a 6 TM channel. The ion pore regions (S5, Ploop, and S6) are shown in red. Also shown are the S1–S4 domain and a C-terminal cytoplasmic domain [CNB domain (CNBD)]. (B) MlotiK1 structure viewed from the extracellular side. One subunit is shown in red. TMs are labeled S1 to S6. Green spheres in the pore are K^+. (C) Stereo side view of the MlotiK1 channel structure. Extracellular side at the top of figure. Subunits are shown in different colors. Some of the TMs and the S4–S5 linker are labeled. One of the C termini is indicated by C.

Figure 5.
The S4 helix. (A) Stereo side view of MlotiK1 and Kv1.2 S1–S4 domains superposed via S2 and S1. 3[10] regions in S4 of MlotiK1 and Kv1.2 are shown in red and cyan, respectively. Other TMs are represented by brown ribbons. S4 residues discussed in the text are labeled. (B) Extracellular view of S1–S4 domains from MlotiK1 and Kv1.2 superposed via S2 and S1. 3[10] regions in S4 as in A. Other helical regions are in white ribbons. Kv1.2 R1, R2, R3, R4, K5, and R6 and equivalent MlotiK1 Cα atoms are shown as blue and black spheres, respectively. (C) Surface representation of MlotiK1 S1–S4 domain. S4 is shown as a red ribbon, with residues equivalent to R2, R3, R4, K5, and R6 shown as sticks. Protein regions from S1 to S3 are shown as gray surface representations. S1, S2, and S3 helices are shown as green ribbons inside the surface. (D) Same as in C but viewed from the extracellular side.

Figures were selected by an automated process.