PDBsum entry 1vng

Haloperoxidase

PDB id: 1vng

Contents

Protein chain

574 a.a. *

Ligands

VO4

Waters ×216

* Residue conservation analysis

PDB id:

1vng

Name:

Haloperoxidase

Title:

Chloroperoxidase from the fungus curvularia inaequalis: mutant h404a

Structure:

Vanadium chloroperoxidase. Chain: a. Engineered: yes. Mutation: yes

Source:

Curvularia inaequalis. Organism_taxid: 38902. Expressed in: saccharomyces cerevisiae. Expression_system_taxid: 4932

Biol. unit:

Monomer (from PDB file)

Resolution:

2.20Å R-factor: 0.180 R-free: 0.210

Authors:

S.Macedo-Ribeiro,A.Messerschmidt

Key ref:

S.Macedo-Ribeiro et al. (1999). X-ray crystal structures of active site mutants of the vanadium-containing chloroperoxidase from the fungus Curvularia inaequalis. J Biol Inorg Chem, 4, 209-219. PubMed id: 10499093

Date:

20-Jan-99 Release date: 11-Aug-99

Protein chain

P49053  (PRXC_CURIN) -  Vanadium chloroperoxidase from Curvularia inaequalis

Seq: 609 a.a.

Struc: 574 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.1.11.1.10 - chloride peroxidase.
• Reaction: RH + Cl^- + H2O2 = RCl + 2 H2O
• Cofactor: Heme

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

reference

J Biol Inorg Chem 4:209-219 (1999)

PubMed id: 10499093

X-ray crystal structures of active site mutants of the vanadium-containing chloroperoxidase from the fungus Curvularia inaequalis.

S.Macedo-Ribeiro, W.Hemrika, R.Renirie, R.Wever, A.Messerschmidt.

ABSTRACT

The X-ray structures of the chloroperoxidase from Curvularia inaequalis, heterologously expressed in Saccharomyces cerevisiae, have been determined both in its apo and in its holo forms at 1.66 and 2.11 A resolution, respectively. The crystal structures reveal that the overall structure of this enzyme remains nearly unaltered, particularly at the metal binding site. At the active site of the apo-chloroperoxidase structure a clearly defined sulfate ion was found, partially stabilised through electrostatic interactions and hydrogen bonds with positively charged residues involved in the interactions with the vanadate in the native protein. The vanadate binding pocket seems to form a very rigid frame stabilising oxyanion binding. The rigidity of this active site matrix is the result of a large number of hydrogen bonding interactions involving side chains and the main chain of residues lining the active site. The structures of single site mutants to alanine of the catalytic residue His404 and the vanadium protein ligand His496 have also been analysed. Additionally we determined the structural effects of mutations to alanine of residue Arg360, directly involved in the compensation of the negative charge of the vanadate group, and of residue Asp292 involved in forming a salt bridge with Arg490 which also interacts with the vanadate. The enzymatic chlorinating activity is drastically reduced to approximately 1% in mutants D292A, H404A and H496A. The structures of the mutants confirm the view of the active site of this chloroperoxidase as a rigid matrix providing an oxyanion binding site. No large changes are observed at the active site for any of the analysed mutants. The empty space left by replacement of large side chains by alanines is usually occupied by a new solvent molecule which partially replaces the hydrogen bonding interactions to the vanadate. The new solvent molecules additionally replace part of the interactions the mutated side chains were making to other residues lining the active site frame. When this is not possible, another side chain in the proximity of the mutated residue moves in order to satisfy the hydrogen bonding potential of the residues located at the active site frame.