PDBsum entry 1s5h

Membrane protein

PDB id: 1s5h

Contents

Protein chains

211 a.a. *

219 a.a. *

103 a.a. *

Ligands

F09

DGA

Metals

__K ×7

Waters ×228

* Residue conservation analysis

PDB id:

1s5h

Name:

Membrane protein

Title:

Potassium channel kcsa-fab complex t75c mutant in k+

Structure:

Antibody fab fragment light chain. Chain: a. Antibody fab fragment heavy chain. Chain: b. Voltage-gated potassium channel. Chain: c. Engineered: yes. Mutation: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Streptomyces coelicolor, streptomyces lividans. ,. Organism_taxid: 1902,1916. Strain: ,. Gene: kcsa, skc1, sco7660, sc10f4.33. Expressed in: escherichia coli.

Biol. unit:

Dodecamer (from PDB file)

Resolution:

2.20Å R-factor: 0.222 R-free: 0.240

Authors:

R.Mackinnon,M.Zhou

Key ref:

M.Zhou and R.MacKinnon (2004). A mutant KcsA K(+) channel with altered conduction properties and selectivity filter ion distribution. J Mol Biol, 338, 839-846. PubMed id: 15099749 DOI: 10.1016/j.jmb.2004.03.020

Date:

20-Jan-04 Release date: 18-May-04

Protein chain

No UniProt id for this chain

Struc: 211 a.a.

Protein chain

No UniProt id for this chain

Struc: 219 a.a.

Protein chain

P0A333  (KCSA_STRCO) -  pH-gated potassium channel KcsA from Streptomyces coelicolor (strain ATCC BAA-471 / A3(2) / M145)

Seq: 160 a.a.

Struc: 103 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1016/j.jmb.2004.03.020

J Mol Biol 338:839-846 (2004)

PubMed id: 15099749

A mutant KcsA K(+) channel with altered conduction properties and selectivity filter ion distribution.

M.Zhou, R.MacKinnon.

ABSTRACT

The selectivity filter of K(+) channels is comprised of a linear queue of four equal-spaced ion-binding sites spanning a distance of 12A. Each site is formed of eight oxygen atoms from the protein. The first three sites, numbered 1-3 from the extracellular side, are made of exclusively main-chain carbonyl oxygen atoms. The fourth site, closest to the intracellular side, is made of four main-chain carbonyl oxygen atoms and four threonine side-chain hydroxyl oxygen atoms. Here we characterize the effects of mutating the threonine to cysteine on the distribution of ions in the selectivity filter and on the conduction of ions through the filter. The mutation influences the occupancy of K(+) at sites 2 and 4 and it reduces the maximum rate of conduction in the limit of high K(+) concentration. The mutation does not affect the conduction of Rb(+). These results can be understood in the context of a conduction mechanism in which a pair of K ions switch between energetically balanced 1,3 and 2,4 configurations.

Selected figure(s)

Figure 2.
Figure 2. A, Stereo view of the selectivity filter region for the T75C mutant KcsA channel. The structure, solved in 200 mM K+, is shown with residues E71 to D80 (from two diagonally opposed subunits) rendered in a ball-and-stick representation. Green spheres represent K+ binding sites in the filter, and the magenta sphere represents a site with residual electron density. The 2F[o] -F[c] electron density map (contoured at 2s) validating the structure is shown as a blue mesh. B, Stereo view of the selectivity filter region for the wild-type KcsA. The structure (PDB code 1K4C[3.]), solved in 200 mM K+, is represented in the same way as in A. C, Stereo view of the selectivity filter region of the T75C (red) superimposed on that of the wild-type (blue).

Figure 5.
Figure 5. Comparison of K+ and Rb^+ conduction properties in the wild-type KcsA. Cord conductances (180 mV) are plotted against either K+ or Rb^+ concentrations. The data in this Figure are from Figure 3(A) of Morais-Cabral et al.[2.]

The above figures are reprinted by permission from Elsevier: J Mol Biol (2004, 338, 839-846) copyright 2004.

Figures were selected by an automated process.