PDBsum entry 1foh

Flavin

PDB id: 1foh

Contents

Protein chains

649 a.a. *

Ligands

FAD ×4

IPH ×4

Waters ×1189

* Residue conservation analysis

PDB id:

1foh

Name:

Flavin

Title:

Phenol hydroxylase from trichosporon cutaneum

Structure:

Phenol hydroxylase. Chain: a, b, c, d. Engineered: yes

Source:

Trichosporon cutaneum. Organism_taxid: 5554. Cell_line: 293. Collection: atcc 46490. Gene: phya. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.40Å R-factor: 0.217 R-free: 0.278

Authors:

C.Enroth,H.Neujahr,G.Schneider,Y.Lindqvist

Key ref:

C.Enroth et al. (1998). The crystal structure of phenol hydroxylase in complex with FAD and phenol provides evidence for a concerted conformational change in the enzyme and its cofactor during catalysis. Structure, 6, 605-617. PubMed id: 9634698 DOI: 10.1016/S0969-2126(98)00062-8

Date:

26-Mar-98 Release date: 17-Jun-98

Protein chains

P15245  (PHHY_CUTCT) -  Phenol hydroxylase from Cutaneotrichosporon cutaneum

Seq: 665 a.a.

Struc: 649 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.1.14.13.7 - phenol 2-monooxygenase (NADPH).
• Reaction: phenol + NADPH + O2 + H⁺ = catechol + NADP⁺ + H2O

phenol + NADPH + O2 + H(+) (Bound ligand (Het Group name = IPH) corresponds exactly) = catechol + NADP(+) + H2O

• Cofactor: FAD

FAD (Bound ligand (Het Group name = FAD) corresponds exactly)

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

reference

DOI no: 10.1016/S0969-2126(98)00062-8

Structure 6:605-617 (1998)

PubMed id: 9634698

The crystal structure of phenol hydroxylase in complex with FAD and phenol provides evidence for a concerted conformational change in the enzyme and its cofactor during catalysis.

C.Enroth, H.Neujahr, G.Schneider, Y.Lindqvist.

ABSTRACT

BACKGROUND: The synthesis of phenolic compounds as by-products of industrial reactions poses a serious threat to the environment. Understanding the enzymatic reactions involved in the degradation and detoxification of these compounds is therefore of much interest. Soil-living yeasts use flavin adenine dinucleotide (FAD)-containing enzymes to hydroxylate phenols. This reaction initiates a metabolic sequence permitting utilisation of the aromatic compound as a source of carbon and energy. The phenol hydroxylase from Trichosporon cutaneum hydroxylates phenol to catechol. Phenol is the best substrate, but the enzyme also accepts simple hydroxyl-, amino-, halogen- or methyl-substituted phenols. RESULTS: The crystal structure of phenol hydroxylase in complex with FAD and phenol has been determined at 2.4 A resolution. The structure was solved by the MIRAS method. The protein model consists of two homodimers. The subunit consists of three domains, the first of which contains a beta sheet that binds FAD with a typical beta alpha beta nucleotide-binding motif and also a fingerprint motif for NADPH binding. The active site is located at the interface between the first and second domains; the second domain also binds the phenolic substrate. The third domain contains a thioredoxin-like fold and is involved in dimer contacts. The subunits within the dimer show substantial differences in structure and in FAD conformation. This conformational flexibility allows the substrate to gain access to the active site and excludes solvent during the hydroxylation reaction. CONCLUSIONS: Two of the domains of phenol hydroxylase are similar in structure to p-hydroxybenzoate hydroxylase. Thus, phenol hydroxylase is a member of a family of flavin-containing aromatic hydroxylases that share the same overall fold, in spite of large differences in amino acid sequences and chain length. The structure of phenol hydroxylase is consistent with a hydroxyl transfer mechanism via a peroxo-FAD intermediate. We propose that a movement of FAD takes place in concert with a large conformational change of residues 170-210 during catalysis.

Selected figure(s)

Figure 6.
Figure 6. Schematic drawing of the FAD-binding site of phenol hydroxylase in (a) the `in' conformation and (b) the `out' conformation. The two conformations are stabilised by hydrogen bonds, but the bonding pattern is significantly different in the two states. Most notable are the hydrogen bonds from the isoalloxazine ring to the mainchain nitrogen atoms of residues Gly55, Gly369, Met370 and Asn371, which are all broken and in some cases exchanged to hydrogen bonds to water molecules in the out conformation. Residue His 189 (in (a)), depicted with an asterisk, is located in the flexible segment of the polypeptide chain and consequently does not make contacts to FAD in the out conformation, where the loop is in the open conformation. In addition, residues 43-52 move slightly between the two conformations, in concert with the movement of the isoalloxazine ring. Most notable here is Gln52, which works as a hinge for this stretch of residues. In the in case Gln52 is hydrogen bonded to an oxygen atom of the ribityl chain; in the out case Gln52 has moved its sidechain to lie parallel to the isoalloxazine ring. A new hydrogen bond is formed from the same oxygen, but this time to Gln117. Most of the hydrogen bonds to FAD are conserved for this class of aromatic hydroxylases.

The above figure is reprinted by permission from Cell Press: Structure (1998, 6, 605-617) copyright 1998.

Figure was selected by an automated process.