PDBsum entry 2q2c

Transport protein

PDB id: 2q2c

Contents

Protein chains

231 a.a. *

Ligands

SO4 ×5

HIS ×4

GOL ×2

Waters ×442

* Residue conservation analysis

PDB id:

2q2c

Name:

Transport protein

Title:

Crystal structures of the arginine-, lysine-, histidine-binding protein artj from the thermophilic bacterium geobacillus stearothermophilus

Structure:

Artj. Chain: a, b, c, d. Engineered: yes. Mutation: yes

Source:

Geobacillus stearothermophilus. Organism_taxid: 1422. Strain: geobacillus stearothermophilus dsmz 13240. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.35Å R-factor: 0.270 R-free: 0.333

Authors:

A.Vahedi-Faridi,F.Scheffel,V.Eckey,W.Saenger,E.Schneider

Key ref:

A.Vahedi-Faridi et al. (2008). Crystal structures and mutational analysis of the arginine-, lysine-, histidine-binding protein ArtJ from Geobacillus stearothermophilus. Implications for interactions of ArtJ with its cognate ATP-binding cassette transporter, Art(MP)2. J Mol Biol, 375, 448-459. PubMed id: 18022195 DOI: 10.1016/j.jmb.2007.10.049

Date:

28-May-07 Release date: 15-Jan-08

Protein chains

D0VWX8  (D0VWX8_GEOSE) -  ArtJ from Geobacillus stearothermophilus

Seq: 252 a.a.

Struc: 231 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.jmb.2007.10.049

J Mol Biol 375:448-459 (2008)

PubMed id: 18022195

Crystal structures and mutational analysis of the arginine-, lysine-, histidine-binding protein ArtJ from Geobacillus stearothermophilus. Implications for interactions of ArtJ with its cognate ATP-binding cassette transporter, Art(MP)2.

A.Vahedi-Faridi, V.Eckey, F.Scheffel, C.Alings, H.Landmesser, E.Schneider, W.Saenger.

ABSTRACT

ArtJ is the substrate-binding component (receptor) of the ATP-binding cassette (ABC) transport system ArtJ-(MP)(2) from the thermophilic bacterium Geobacillus stearothermophilus that is specific for arginine, lysine, and histidine. The highest affinity is found for arginine (K(d)=0.039(+/-0.014) microM), while the affinities for lysine and histidine are about tenfold lower. We have determined the X-ray structures of ArtJ liganded with each of these substrates at resolutions of 1.79 A (arginine), 1.79 A (lysine), and 2.35 A (histidine), respectively. As found for other solute receptors, the polypeptide chain is folded into two distinct domains (lobes) connected by a hinge. The interface between the lobes forms the substrate-binding pocket whose geometry is well preserved in all three ArtJ/amino acid complexes. Structure-derived mutational analyses indicated the crucial role of a region in the carboxy-terminal lobe of ArtJ in contacting the transport pore Art(MP)(2) and revealed the functional importance of Gln132 and Trp68. While variant Gln132Leu exhibited lower binding affinity for arginine but no binding of lysine and histidine, the variant Trp68Leu had lost binding activity for all three substrates. The results are discussed in comparison with known structures of homologous proteins from mesophilic bacteria.

Selected figure(s)

Figure 4.
Figure 4. Detailed view of the ArtJ-Arg binding pocket. (a) Polar and hydrophobic interaction sites between the arginine ligand and lobe I are indicated, Phe31 of the hydrophobic sandwich Phe31/Trp68 is not shown. (b) Polar interactions between the arginine ligand and lobe II, rotated with respect to (a). (c) Electrostatic surface representation (red, negative; blue, positive; yellow, neutral) of the cage-like structure of the binding pocket, Arg is indicated by a wire model. The direction of view is approximately along the arginine side-chain.

Figure 6.
Figure 6. Comparison of the ArtJ-His (grey) and HisJ (green) binding pockets. (a) Only differing residues are shown: HisJ-Thr195 → ArtJ-Tyr205, HisJ-Leu117 → ArtJ-Gln132, HisJ-Gln122 → ArtJ-H[2]O and ArtJ-Glu203 → HisJ-H[2]O, ArtJ-Asp28 → HisJ-Asp11. Gln132 O^ε of ArtJ provides a hydrogen bond to histidine that is not present in HisJ. (b) Hydrophobic sandwich formed by the side-chain of bound histidine and type conserved Trp68/Phe31 and Leu2/Tyr14, respectively.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2008, 375, 448-459) copyright 2008.

Figures were selected by an automated process.