PDBsum entry 1wzf

Oxidoreductase

PDB id: 1wzf

Contents

Protein chains

209 a.a. *

Ligands

SO4 ×3

YOL ×2

GOL

Waters ×260

* Residue conservation analysis

PDB id:

1wzf

Name:

Oxidoreductase

Title:

Crystal structure of an artificial metalloprotein: fe(10-cooh- salophen)/wild type heme oxygenase

Structure:

Heme oxygenase. Chain: a, b. Engineered: yes

Source:

Corynebacterium diphtheriae. Organism_taxid: 1717. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.85Å R-factor: 0.188 R-free: 0.235

Authors:

M.Unno,N.Yokoi,T.Ueno,Y.Watanabe,M.Ikeda-Saito

Key ref:

T.Ueno et al. (2006). Design of metal cofactors activated by a protein-protein electron transfer system. Proc Natl Acad Sci U S A, 103, 9416-9421. PubMed id: 16769893 DOI: 10.1073/pnas.0510968103

Date:

04-Mar-05 Release date: 21-Feb-06

Protein chains

P71119  (HMUO_CORDI) -  Heme oxygenase from Corynebacterium diphtheriae (strain ATCC 700971 / NCTC 13129 / Biotype gravis)

Seq: 215 a.a.

Struc: 209 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.1.14.14.18 - heme oxygenase (biliverdin-producing).
• Reaction: heme b + 3 reduced [NADPH--hemoprotein reductase] + 3 O2 = biliverdin IXalpha + CO + Fe²⁺ + 3 oxidized [NADPH--hemoprotein reductase] + 3 H2O + H⁺

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

reference

DOI no: 10.1073/pnas.0510968103

Proc Natl Acad Sci U S A 103:9416-9421 (2006)

PubMed id: 16769893

Design of metal cofactors activated by a protein-protein electron transfer system.

T.Ueno, N.Yokoi, M.Unno, T.Matsui, Y.Tokita, M.Yamada, M.Ikeda-Saito, H.Nakajima, Y.Watanabe.

ABSTRACT

Protein-to-protein electron transfer (ET) is a critical process in biological chemistry for which fundamental understanding is expected to provide a wealth of applications in biotechnology. Investigations of protein-protein ET systems in reductive activation of artificial cofactors introduced into proteins remains particularly challenging because of the complexity of interactions between the cofactor and the system contributing to ET. In this work, we construct an artificial protein-protein ET system, using heme oxygenase (HO), which is known to catalyze the conversion of heme to biliverdin. HO uses electrons provided from NADPH/cytochrome P450 reductase (CPR) through protein-protein complex formation during the enzymatic reaction. We report that a Fe(III)(Schiff-base), in the place of the active-site heme prosthetic group of HO, can be reduced by NADPH/CPR. The crystal structure of the Fe(10-CH(2)CH(2)COOH-Schiff-base).HO composite indicates the presence of a hydrogen bond between the propionic acid carboxyl group and Arg-177 of HO. Furthermore, the ET rate from NADPH/CPR to the composite is 3.5-fold faster than that of Fe(Schiff-base).HO, although the redox potential of Fe(10-CH(2)CH(2)COOH-Schiff-base).HO (-79 mV vs. NHE) is lower than that of Fe(Schiff-base).HO (+15 mV vs. NHE), where NHE is normal hydrogen electrode. This work describes a synthetic metal complex activated by means of a protein-protein ET system, which has not previously been reported. Moreover, the result suggests the importance of the hydrogen bond for the ET reaction of HO. Our Fe(Schiff-base).HO composite model system may provide insights with regard to design of ET biosystems for sensors, catalysts, and electronics devices.

Selected figure(s)

Figure 1.
Fig. 1. Catalytic reaction of HO. (A) Enzymatic cycle of heme metabolism to biliverdin catalyzed by HO. The reactions shaded in blue indicate the ET step from CPR to heme to be used for the reduction of Fe^III(Schiff-base) complexes. (B) Chemical structures of heme (Left) and Fe^III(Schiff-base) (Right).

Figure 2.
Fig. 2. Close-up views of coordination geometries of the metal cofactors in the HO active-site region. Refined model coordinates for the active site region are superimposed on 2F[o] – F[c] maps contoured at 1.0 , except for heme·HO, with elements of the protein and cofactors in ball-and-stick models for top (Left) and side (Right) views. Green is carbon, and purple, red, and pink are nitrogen, oxygen, and iron, respectively. (A) Heme·HO. (B) 1·HO refined to 1.35 Å. (C) 2·HO refined to 1.85 Å. (D) 3·HO refined to 1.75 Å.

Figures were selected by an automated process.