PDBsum entry 5a40

Transport protein

PDB id: 5a40

Contents

Protein chains

127 a.a.

90 a.a.

Metals

_HG ×4

PDB id:

5a40

Name:

Transport protein

Title:

Crystal structure of a dual topology fluoride ion channel.

Structure:

Putative fluoride ion transporter crcb. Chain: a, b, c, d. Synonym: fluoride channel. Engineered: yes. Mutation: yes. Monobodies. Chain: e, f, g, h. Engineered: yes

Source:

Bordetella pertussis. Organism_taxid: 520. Strain: tohama 1. Atcc: baa-589. Expressed in: escherichia coli. Expression_system_taxid: 469008. Homo sapiens. Human. Organism_taxid: 9606.

Resolution:

3.60Å R-factor: 0.236 R-free: 0.270

Authors:

R.B.Stockbridge,L.Kolmakova-Partensky,T.Shane,A.Koide,S.Koide, C.Miller,S.Newstead

Key ref:

R.B.Stockbridge et al. (2015). Crystal structures of a double-barrelled fluoride ion channel. Nature, 525, 548-551. PubMed id: 26344196 DOI: 10.1038/nature14981

Date:

04-Jun-15 Release date: 02-Sep-15

Protein chains

Q7VYU0  (CRCB_BORPE) -  Fluoride-specific ion channel FluC from Bordetella pertussis (strain Tohama I / ATCC BAA-589 / NCTC 13251)

Seq: 128 a.a.

Struc: 127 a.a.*

Protein chains

No UniProt id for this chain

Struc: 90 a.a.

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B, C, D: E.C.?

DOI no: 10.1038/nature14981

Nature 525:548-551 (2015)

PubMed id: 26344196

Crystal structures of a double-barrelled fluoride ion channel.

R.B.Stockbridge, L.Kolmakova-Partensky, T.Shane, A.Koide, S.Koide, C.Miller, S.Newstead.

ABSTRACT

To contend with hazards posed by environmental fluoride, microorganisms export this anion through F(-)-specific ion channels of the Fluc family. Since the recent discovery of Fluc channels, numerous idiosyncratic features of these proteins have been unearthed, including strong selectivity for F(-) over Cl(-) and dual-topology dimeric assembly. To understand the chemical basis for F(-) permeation and how the antiparallel subunits convene to form a F(-)-selective pore, here we solve the crystal structures of two bacterial Fluc homologues in complex with three different monobody inhibitors, with and without F(-) present, to a maximum resolution of 2.1 Å. The structures reveal a surprising 'double-barrelled' channel architecture in which two F(-) ion pathways span the membrane, and the dual-topology arrangement includes a centrally coordinated cation, most likely Na(+). F(-) selectivity is proposed to arise from the very narrow pores and an unusual anion coordination that exploits the quadrupolar edges of conserved phenylalanine rings.