PDBsum entry: 2h8p

Membrane protein

PDB id: 2h8p

Contents

Protein chains

219 a.a. *

212 a.a. *

57 a.a. *

43 a.a. *

Ligands

GOA

B3H

Metals

__K ×6

Waters ×90

* Residue conservation analysis

PDB id:

2h8p

Name:

Membrane protein

Title:

Structure of a k channel with an amide to ester substitution selectivity filter

Structure:

Fab heavy chain. Chain: a. Engineered: yes. Fab light chain. Chain: b. Engineered: yes. Kcsa channel. Chain: c. Fragment: residues 1-79.

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Expressed in: escherichia coli. Expression_system_taxid: 562. Synthetic: yes. Other_details: the peptide was synthesized by the expressed ligation reaction between a recombinant peptide thioester a synthetic peptide consisting of a n-terminal cysteine..

Biol. unit:

60mer (from PDB file)

Resolution:

2.25Å R-factor: 0.233 R-free: 0.242

Authors:

F.I.Valiyaveetil,R.Mackinnon,T.W.Muir

Key ref:

F.I.Valiyaveetil et al. (2006). Structural and functional consequences of an amide-to-ester substitution in the selectivity filter of a potassium channel. J Am Chem Soc, 128, 11591-11599. PubMed id: 16939283 DOI: 10.1021/ja0631955

Date:

07-Jun-06 Release date: 12-Sep-06

Protein chain

No UniProt id for this chain

Protein chain

No UniProt id for this chain

Protein chain

P0A334  (KCSA_STRLI) -  Voltage-gated potassium channel

Seq: 160 a.a.

Struc: 57 a.a.*

Protein chain

	No UniProt id for this chain
	* PDB and UniProt seqs differ at 2 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Biochemical function: protein binding (1 term)

DOI no: 10.1021/ja0631955

J Am Chem Soc 128:11591-11599 (2006)

PubMed id: 16939283

Structural and functional consequences of an amide-to-ester substitution in the selectivity filter of a potassium channel.

F.I.Valiyaveetil, M.Sekedat, R.MacKinnon, T.W.Muir.

ABSTRACT

The selectivity filter of K(+) channels comprises four contiguous ion binding sites, S1 through S4. Structural and functional data indicate that the filter contains on average two K(+) ions at any given time and that these ions reside primarily in two configurations, namely to sites S1 and S3 or to sites S2 and S4. Maximum ion flux through the channel is expected to occur when the energy difference between these two binding configurations is zero. In this study, we have used protein semisynthesis to selectively perturb site 1 within the filter of the KcsA channel through use of an amide-to-ester substitution. The modification alters K(+) conduction properties. The structure of the selectivity filter is largely unperturbed by the modification, despite the loss of an ordered water molecule normally located just behind the filter. Introduction of the ester moiety was found to alter the distribution of K(+), Rb(+,) and Cs(+) within the filter, with the most dramatic change found for Rb(+). The redistribution of ions is associated with the appearance of a partially hydrated ion just external to the filter, at a position where no ion is observed in the wild-type channel. The appearance of this new ion-binding site creates a change in the distance between a pair of K(+) ions some fraction of the time, apparently leading to a reduction in the ion conduction rate. Importantly, this finding suggests that the selectivity filter of a potassium channel is optimized both in terms of absolute ion occupancy and in terms of the separation in distance between the conducting ions.