PDBsum entry 2caq

Transferase

PDB id: 2caq

Contents

Protein chain

204 a.a. *

Ligands

GSH

PG4

BME

Waters ×197

* Residue conservation analysis

PDB id:

2caq

Name:

Transferase

Title:

Structure of r21l mutant of sh28gst in complex with gsh

Structure:

Glutathione s-transferase 28 kda. Chain: a. Synonym: gst 28, gst class-sigma. Engineered: yes. Mutation: yes

Source:

Schistosoma haematobium. Blood fluke. Organism_taxid: 6185. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.00Å R-factor: 0.190 R-free: 0.240

Authors:

P.Baiocco,L.J.Gourlay,F.Angelucci,A.Bellelli,A.E.Miele,M.Brunori

Key ref:

P.Baiocco et al. (2006). Probing the mechanism of GSH activation in Schistosoma haematobium glutathione-S-transferase by site-directed mutagenesis and X-ray crystallography. J Mol Biol, 360, 678-689. PubMed id: 16777141 DOI: 10.1016/j.jmb.2006.05.040

Date:

22-Dec-05 Release date: 21-Jun-06

Protein chain

P30113  (GST28_SCHBO) -  Glutathione S-transferase class-mu 28 kDa isozyme from Schistosoma bovis

Seq: 211 a.a.

Struc: 204 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.2.5.1.18 - glutathione transferase.
• Reaction: RX + glutathione = an S-substituted glutathione + a halide anion + H⁺

RX (Bound ligand (Het Group name = GSH) corresponds exactly) + glutathione = S-substituted glutathione + halide anion + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

DOI no: 10.1016/j.jmb.2006.05.040

J Mol Biol 360:678-689 (2006)

PubMed id: 16777141

Probing the mechanism of GSH activation in Schistosoma haematobium glutathione-S-transferase by site-directed mutagenesis and X-ray crystallography.

P.Baiocco, L.J.Gourlay, F.Angelucci, J.Fontaine, M.Hervé, A.E.Miele, F.Trottein, M.Brunori, A.Bellelli.

ABSTRACT

During turnover, the catalytic tyrosine residue (Tyr10) of the sigma class Schistosoma haematobium wild-type glutathione-S-transferase is expected to switch alternately in and out of the reduced glutathione-binding site (G-site). The Tyrout10 conformer forms a pi-cation interaction with the guanidinium group of Arg21. As in other similar glutathione-S-transferases, the catalytic Tyr has a low pKa of 7.2. In order to investigate the catalytic role of Tyr10, and the structural and functional roles of Arg21, we carried out structural studies on two Arg21 mutants (R21L and R21Q) and a Tyr10 mutant, Y10F. Our crystallographic data for the two Arg21 mutants indicate that only the Tyrout10 conformation is populated, thereby excluding a role of Arg21 in the stabilisation of the out conformation. However, Arg21 was confirmed to be catalytically important and essential for the low pKa of Tyr10. Upon comparison with structural data generated for reduced glutathione-bound and inhibitor-bound wild-type enzymes, it was observed that the orientations of Tyr10 and Arg35 are concerted and that, upon ligand binding, minor rearrangements occur within conserved residues in the active site loop. These rearrangements are coupled to quaternary rigid-body movements at the dimer interface and alterations in the localisation and structural order of the C-terminal domain.

Selected figure(s)

Figure 1.
Figure 1. The movement of conserved Arg35. The two alternative positions of Arg35 were observed in the structures of (a) GTX-bound wtGST showing only the Tyr^in10 conformer and (b) R21L showing the Tyr^out10 conformer. Arg35 is indicated by green sticks, whereas other important residues are indicated by blue sticks. This Figure was generated using ViewerLite 4.2 (Accelrys Inc.).

Figure 2.
Figure 2. Stereo views of the electron density (2F[o]–F[c] at 1σ) showing the two conformers of Tyr10 in the G-site. (a) R21L, showing Tyr^out10 at H-bond distance from Asp33. The new residue, Leu21 is at a distance of 4 Å from Tyr10. Tyr^out10 hinders the movement of the Arg35 side-chain, as displayed in Figure 1(b). (b) GTX-bound wtGST, showing the polar interaction between the hydroxyl group of the Tyr^in10 and the sulphur atom of GTX. Tyr10, Arg21, Asp33 and Arg35 are orientated as shown in Figure 1(a).

The above figures are reprinted by permission from Elsevier: J Mol Biol (2006, 360, 678-689) copyright 2006.

Figures were selected by an automated process.