PDBsum entry 4j7c

Transport protein

PDB id: 4j7c

Contents

Protein chains

(+ 2 more) 216 a.a.

429 a.a.

Ligands

ATP ×8

Metals

__K ×4

PDB id:

4j7c

Name:

Transport protein

Title:

Ktrab potassium transporter from bacillus subtilis

Structure:

Ktr system potassium uptake protein a. Chain: a, b, c, d, e, f, g, h. Synonym: k(+)-uptake protein ktra. Engineered: yes. Mutation: yes. Ktr system potassium uptake protein b. Chain: i, j, k, l. Synonym: k(+)-uptake protein ktrb. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 224308. Strain: 168. Gene: ktra. Expressed in: escherichia coli. Expression_system_taxid: 562. Gene: ktrb.

Resolution:

3.50Å R-factor: 0.259 R-free: 0.273

Authors:

R.S.Vieira-Pires,J.H.Morais-Cabral

Key ref:

R.S.Vieira-Pires et al. (2013). The structure of the KtrAB potassium transporter. Nature, 496, 323-328. PubMed id: 23598340 DOI: 10.1038/nature12055

Date:

13-Feb-13 Release date: 17-Apr-13

Protein chains

O32080  (KTRA_BACSU) -  Ktr system potassium uptake protein A from Bacillus subtilis (strain 168)

Seq: 222 a.a.

Struc: 216 a.a.*

Protein chains

O32081  (KTRB_BACSU) -  Ktr system potassium uptake protein B from Bacillus subtilis (strain 168)

Seq: 445 a.a.

Struc: 429 a.a.

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

Enzyme reactions

• Enzyme class: Chains A, B, C, D, E, F, G, H, I, J, K, L: E.C.?

DOI no: 10.1038/nature12055

Nature 496:323-328 (2013)

PubMed id: 23598340

The structure of the KtrAB potassium transporter.

R.S.Vieira-Pires, A.Szollosi, J.H.Morais-Cabral.

ABSTRACT

In bacteria, archaea, fungi and plants the Trk, Ktr and HKT ion transporters are key components of osmotic regulation, pH homeostasis and resistance to drought and high salinity. These ion transporters are functionally diverse: they can function as Na(+) or K(+) channels and possibly as cation/K(+) symporters. They are closely related to potassium channels both at the level of the membrane protein and at the level of the cytosolic regulatory domains. Here we describe the crystal structure of a Ktr K(+) transporter, the KtrAB complex from Bacillus subtilis. The structure shows the dimeric membrane protein KtrB assembled with a cytosolic octameric KtrA ring bound to ATP, an activating ligand. A comparison between the structure of KtrAB-ATP and the structures of the isolated full-length KtrA protein with ATP or ADP reveals a ligand-dependent conformational change in the octameric ring, raising new ideas about the mechanism of activation in these transporters.