PDBsum entry 2bbh

Metal transport/membrane protein

PDB id: 2bbh

Contents

Protein chain

223 a.a. *

Ligands

DMU ×4

Metals

_MG

_NA

Waters ×236

* Residue conservation analysis

PDB id:

2bbh

Name:

Metal transport/membrane protein

Title:

X-ray structure of t.Maritima cora soluble domain

Structure:

Divalent cation transport-related protein. Chain: a. Fragment: residues 1-266. Engineered: yes. Mutation: yes

Source:

Thermotoga maritima. Organism_taxid: 2336. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Biol. unit:

Dimer (from PQS)

Resolution:

1.85Å R-factor: 0.198 R-free: 0.233

Authors:

V.V.Lunin,E.Dobrovetsky,G.Khutoreskaya,A.Bochkarev,M.E.Maguire, A.M.Edwards,C.M.Koth,Structural Genomics Consortium (Sgc)

Key ref:

V.V.Lunin et al. (2006). Crystal structure of the CorA Mg2+ transporter. Nature, 440, 833-837. PubMed id: 16598263 DOI: 10.1038/nature04642

Date:

17-Oct-05 Release date: 13-Dec-05

Protein chain

Q9WZ31  (CORA_THEMA) -  Cobalt/magnesium transport protein CorA from Thermotoga maritima (strain ATCC 43589 / DSM 3109 / JCM 10099 / NBRC 100826 / MSB8)

Seq: 351 a.a.

Struc: 223 a.a.*

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

DOI no: 10.1038/nature04642

Nature 440:833-837 (2006)

PubMed id: 16598263

Crystal structure of the CorA Mg2+ transporter.

V.V.Lunin, E.Dobrovetsky, G.Khutoreskaya, R.Zhang, A.Joachimiak, D.A.Doyle, A.Bochkarev, M.E.Maguire, A.M.Edwards, C.M.Koth.

ABSTRACT

The magnesium ion, Mg2+, is essential for myriad biochemical processes and remains the only major biological ion whose transport mechanisms remain unknown. The CorA family of magnesium transporters is the primary Mg2+ uptake system of most prokaryotes and a functional homologue of the eukaryotic mitochondrial magnesium transporter. Here we determine crystal structures of the full-length Thermotoga maritima CorA in an apparent closed state and its isolated cytoplasmic domain at 3.9 A and 1.85 A resolution, respectively. The transporter is a funnel-shaped homopentamer with two transmembrane helices per monomer. The channel is formed by an inner group of five helices and putatively gated by bulky hydrophobic residues. The large cytoplasmic domain forms a funnel whose wide mouth points into the cell and whose walls are formed by five long helices that are extensions of the transmembrane helices. The cytoplasmic neck of the pore is surrounded, on the outside of the funnel, by a ring of highly conserved positively charged residues. Two negatively charged helices in the cytoplasmic domain extend back towards the membrane on the outside of the funnel and abut the ring of positive charge. An apparent Mg2+ ion was bound between monomers at a conserved site in the cytoplasmic domain, suggesting a mechanism to link gating of the pore to the intracellular concentration of Mg2+.

Selected figure(s)

Figure 3.
Electrostatic view of CorA.
Positively charged residues are coloured blue and negatively charged or hydroxyl-containing residues are coloured red. Charged residues within the CorA basic sphincter (blue-highlighted region) and cytoplasmic domain (funnel interior and willow helices, red-highlighted regions) are labelled and illustrated as stick models. For better viewing of the funnel interior, two of the CorA monomers were removed from the model.

Figure 5.
Figure 5: Electron density corresponding to protein and bound magnesium. a, A portion of the soluble domain 1.85 Å electron density map in the region of Asp 89, showing electron density for the putative Mg^2+ ion and the water molecules that fill the hexacoordination shell. b, A portion of the 3.9 Å difference Fourier electron density map (purple) showing the putative magnesium ion between monomers. The inset shows the residue Asp 89 in one monomer (pale blue) and Asp 253 in another monomer (green) and a peak in the difference Fourier electron density map.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2006, 440, 833-837) copyright 2006.

Figures were selected by the author.