PDBsum entry 1pl3

Oxidoreductase

PDB id: 1pl3

Contents

Protein chains

186 a.a. *

Ligands

NAG-NAG ×2

HEM ×2

1PG

Metals

_CD ×6

Waters ×336

* Residue conservation analysis

PDB id:

1pl3

Name:

Oxidoreductase

Title:

Cytochrome domain of cellobiose dehydrogenase, m65h mutant

Structure:

Cellobiose dehydrogenase. Chain: a, b. Fragment: cytochrome type b heme domain. Synonym: cdh, cellobiose-quinone oxidoreductase. Engineered: yes. Mutation: yes

Source:

Phanerochaete chrysosporium. Organism_taxid: 5306. Gene: cdh-1 and cdh-2. Expressed in: phanerochaete chrysosporium. Expression_system_taxid: 5306.

Resolution:

1.90Å R-factor: 0.174 R-free: 0.198

Authors:

F.A.J.Rotsaert,B.M.Hallberg,S.De Vries,P.Moenne-Loccoz,C.Divne, M.H.Gold

Key ref:

F.A.Rotsaert et al. (2003). Biophysical and structural analysis of a novel heme B iron ligation in the flavocytochrome cellobiose dehydrogenase. J Biol Chem, 278, 33224-33231. PubMed id: 12796496 DOI: 10.1074/jbc.M302653200

Date:

06-Jun-03 Release date: 01-Jul-03

Protein chains

Q01738  (CDH_PHACH) -  Cellobiose dehydrogenase from Phanerodontia chrysosporium

Seq: 773 a.a.

Struc: 186 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.1.1.99.18 - cellobiose dehydrogenase (acceptor).
• Reaction: D-cellobiose + A = D-cellobiono-1,5-lactone + AH2
• Cofactor: FAD; Heme

FAD Heme (Bound ligand (Het Group name = HEM) matches with 95.45% similarity)

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

reference

DOI no: 10.1074/jbc.M302653200

J Biol Chem 278:33224-33231 (2003)

PubMed id: 12796496

Biophysical and structural analysis of a novel heme B iron ligation in the flavocytochrome cellobiose dehydrogenase.

F.A.Rotsaert, B.M.Hallberg, S.de Vries, P.Moenne-Loccoz, C.Divne, V.Renganathan, M.H.Gold.

ABSTRACT

The fungal extracellular flavocytochrome cellobiose dehydrogenase (CDH) participates in lignocellulose degradation. The enzyme has a cytochrome domain connected to a flavin-binding domain by a peptide linker. The cytochrome domain contains a 6-coordinate low spin b-type heme with unusual iron ligands and coordination geometry. Wild type CDH is only the second example of a b-type heme with Met-His ligation, and it is the first example of a Met-His ligation of heme b where the ligands are arranged in a nearly perpendicular orientation. To investigate the ligation further, Met65 was replaced with a histidine to create a bis-histidyl ligated iron typical of b-type cytochromes. The variant is expressed as a stable 90-kDa protein that retains the flavin domain catalytic reactivity. However, the ability of the mutant to reduce external one-electron acceptors such as cytochrome c is impaired. Electrochemical measurements demonstrate a decrease in the redox midpoint potential of the heme by 210 mV. In contrast to the wild type enzyme, the ferric state of the protoheme displays a mixed low spin/high spin state at room temperature and low spin character at 90 K, as determined by resonance Raman spectroscopy. The wild type cytochrome does not bind CO, but the ferrous state of the variant forms a CO complex, although the association rate is very low. The crystal structure of the M65H cytochrome domain has been determined at 1.9 A resolution. The variant structure confirms a bis-histidyl ligation but reveals unusual features. As for the wild type enzyme, the ligands have a nearly perpendicular arrangement. Furthermore, the iron is bound by imidazole N delta 1 and N epsilon 2 nitrogen atoms, rather than the typical N epsilon 2/N epsilon 2 coordination encountered in bis-histidyl ligated heme proteins. To our knowledge, this is the first example of a bis-histidyl N delta 1/N epsilon 2-coordinated protoporphyrin IX iron.

Selected figure(s)

Figure 3.
FIG. 3. High frequency RR spectra of the oxidized rCDH and the M65H variant, obtained at room temperature (RT, A) and 90 K(B), with Soret excitation (413 nm) in 20 mM sodium succinate, pH 4.5.

Figure 5.
FIG. 5. a, the [A]-weighted F[o] - F[c] electron density around the iron-protoporphyrin IX ring in the M65H cytochrome domain. The 6-coordinate heme iron is ligated by His65 N 1 and His163 N 2. b, superposition of the M65H variant (gold) and wild type (green) heme-binding pocket (Protein Data Bank code 1D7C [PDB] ) (7). The drawings were made with the program Pymol (pymol.sourceforge.net).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 33224-33231) copyright 2003.

Figures were selected by an automated process.