PDBsum entry 2fn0

Transcription

PDB id: 2fn0

Contents

Protein chains

408 a.a. *

Ligands

ACT ×2

PO4 ×2

Metals

_MG ×2

Waters ×550

* Residue conservation analysis

PDB id:

2fn0

Name:

Transcription

Title:

Crystal structure of yersinia enterocolitica salicylate synthase (irp9)

Structure:

Salicylate synthetase, irp9. Chain: a, b. Engineered: yes

Source:

Yersinia enterocolitica. Organism_taxid: 630. Strain: 8081. Gene: irp9. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

1.85Å R-factor: 0.190 R-free: 0.240

Authors:

O.Kerbarh,D.Y.Chirgadze,T.L.Blundell,C.Abell

Key ref:

O.Kerbarh et al. (2006). Crystal structures of Yersinia enterocolitica salicylate synthase and its complex with the reaction products salicylate and pyruvate. J Mol Biol, 357, 524-534. PubMed id: 16434053 DOI: 10.1016/j.jmb.2005.12.078

Date:

10-Jan-06 Release date: 14-Feb-06

Protein chains

Q9X9I8  (Q9X9I8_YEREN) -  Salicylate synthetase, Irp9 from Yersinia enterocolitica

Seq: 434 a.a.

Struc: 408 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.jmb.2005.12.078

J Mol Biol 357:524-534 (2006)

PubMed id: 16434053

Crystal structures of Yersinia enterocolitica salicylate synthase and its complex with the reaction products salicylate and pyruvate.

O.Kerbarh, D.Y.Chirgadze, T.L.Blundell, C.Abell.

ABSTRACT

The salicylate synthase, Irp9, from Yersinia enterocolitica is involved in the biosynthesis of the siderophore yersiniabactin. It is a bifunctional enzyme that forms salicylate and pyruvate from chorismate and water via the intermediate isochorismate. Here we report the first crystal structure of Irp9 and also of its complex with the reaction products salicylate and pyruvate at 1.85 A and 2.1 A resolution, respectively. Like other members of the chorismate-utilizing enzyme family, e.g. the TrpE subunit of anthranilate synthase and the PabB subunit of 4-amino-4-deoxychorismate synthase, Irp9 has a complex alpha/beta fold. The crystal structure of Irp9 contains one molecule each of phosphate and acetate derived from the crystallization buffer. The Irp9-products complex structure was obtained by soaking chorismate into Irp9, demonstrating that the enzyme is still catalytically active in the crystal. Both structures contain Mg(2+) in the active site. There is no evidence of the allosteric tryptophan binding site found in TrpE and PabB. Mutagenesis of Glu240, His321 and Tyr372 provided some insight into the mechanism of the two transformations catalyzed by Irp9. Knowledge of the structure of Irp9 will guide the search for potent inhibitors of salicylate formation, and hence of bacterial iron uptake, which is directly related to the virulence of Yersinia.

Selected figure(s)

Figure 1.
Figure 1. The conversion of chorismate to salicylate and pyruvate occurs in two steps, the conversion of chorismate to isochorismate, catalyzed by ischorismate synthases, and the conversion of isochorismate to salicylate and pyruvate, catalyzed by isochorismate pyruvate lyases. Irp9 has been shown to catalyze both reactions converting chorismate to salicylate via isochorismate.10 Two alternative mechanisms for the pyruvate lyase reactions are shown. In mechanism (a) the acidic (AH) and basic (B) groups are proposed to be Tyr372 and His321, respectively. Mechanism (b) is based on a recent proposal for PchB, a pyruvate lyase.25^ and 26

Figure 5.
Figure 5. Comparison of the C^a-traces of (a) TrpE, (b) PabB and (c) Irp9 protomers and their active sites. Product binding is indicated for each structure in red: benzoate and pyruvate for (a), salicylate and pyruvate for (c). The binding pockets in (a) and (b) for l-tryptophan are also indicated.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2006, 357, 524-534) copyright 2006.

Figures were selected by an automated process.