PDBsum entry 2jbt

Oxidoreductase

PDB id: 2jbt

Contents

Protein chains

400 a.a. *

Ligands

FMN ×4

4HP ×4

Waters ×25

* Residue conservation analysis

PDB id:

2jbt

Name:

Oxidoreductase

Title:

Structure of the monooxygenase component of p-hydroxyphenylacetate hydroxylase from acinetobacter baumannii

Structure:

P-hydroxyphenylacetate hydroxylase c2\:oxygenase component. Chain: a, b, c, d. Synonym: p-hydroxyphenylacetate hydroxylase. Engineered: yes

Source:

Acinetobacter baumannii. Organism_taxid: 470. Expressed in: escherichia coli. Expression_system_taxid: 511693.

Resolution:

2.80Å R-factor: 0.217 R-free: 0.235

Authors:

A.Alfieri,A.Mattevi

Key ref:

A.Alfieri et al. (2007). Structure of the monooxygenase component of a two-component flavoprotein monooxygenase. Proc Natl Acad Sci U S A, 104, 1177-1182. PubMed id: 17227849 DOI: 10.1073/pnas.0608381104

Date:

11-Dec-06 Release date: 23-Jan-07

Protein chains

Q6Q272  (HPAH_ACIBA) -  p-hydroxyphenylacetate 3-hydroxylase, oxygenase component from Acinetobacter baumannii

Seq: 422 a.a.

Struc: 400 a.a.

Enzyme reactions

• Enzyme class: E.C.1.14.14.9 - 4-hydroxyphenylacetate 3-monooxygenase.
• Reaction: 4-hydroxyphenylacetate + FADH2 + O2 = 3,4-dihydroxyphenylacetate + FAD + H2O + H⁺

4-hydroxyphenylacetate + FADH2 (Bound ligand (Het Group name = FMN) matches with 58.49% similarity) + O2 = 3,4-dihydroxyphenylacetate (Bound ligand (Het Group name = 4HP) matches with 91.67% similarity) + FAD + H2O + H(+)

• Cofactor: FAD

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

reference

DOI no: 10.1073/pnas.0608381104

Proc Natl Acad Sci U S A 104:1177-1182 (2007)

PubMed id: 17227849

Structure of the monooxygenase component of a two-component flavoprotein monooxygenase.

A.Alfieri, F.Fersini, N.Ruangchan, M.Prongjit, P.Chaiyen, A.Mattevi.

ABSTRACT

p-Hydroxyphenylacetate hydroxylase from Acinetobacter baumannii is a two-component system consisting of a NADH-dependent FMN reductase and a monooxygenase (C2) that uses reduced FMN as substrate. The crystal structures of C2 in the ligand-free and substrate-bound forms reveal a preorganized pocket that binds reduced FMN without large conformational changes. The Phe-266 side chain swings out to provide the space for binding p-hydroxyphenylacetate that is oriented orthogonal to the flavin ring. The geometry of the substrate-binding site of C2 is significantly different from that of p-hydroxybenzoate hydroxylase, a single-component flavoenzyme that catalyzes a similar reaction. The C2 overall structure resembles the folding of medium-chain acyl-CoA dehydrogenase. An outstanding feature in the C2 structure is a cavity located in front of reduced FMN; it has a spherical shape with a 1.9-A radius and a 29-A3 volume and is interposed between the flavin C4a atom and the substrate atom to be hydroxylated. The shape and position of this cavity are perfectly fit for housing the oxygen atoms of the flavin C4a-hydroperoxide intermediate that is formed upon reaction of the C2-bound reduced flavin with molecular oxygen. The side chain of His-396 is predicted to act as a hydrogen-bond donor to the oxygen atoms of the intermediate. This architecture promotes the nucleophilic attack of the substrate onto the terminal oxygen of the hydroperoxyflavin. Comparative analysis with the structures of other flavoenzymes indicates that a distinctive feature of monooxygenases is the presence of specific cavities that encapsulate and stabilize the crucial hydroperoxyflavin intermediate.

Selected figure(s)

Figure 4.
Fig. 4. Interactions between FMNH^– and C[2]. Distances are in Å and refer to subunit A of C[2]:FMNH^–:HPA structure; # indicates residues from subunit D.

Figure 8.
Fig. 8. Comparison between the active sites of C[2] and glucose oxidase, a fast oxygen-reacting oxidase that does not stabilize flavin C4a-hydroperoxide. A histidine side chain located in front of the flavin is present in both enzymes (His-516 in glucose oxidase and His-396 in C[2]), although with shifted position with respect to the flavin C4 locus. The different positioning of the active site His residues is visualized by superimposing the flavin ring atoms of glucose oxidase (PDB ID code 1GAL) on the equivalent atoms of C[2]. The picture shows His-516 of glucose oxidase (carbons in dark gray) and the model for the C4a-hydroperoxyflavin and His-396 of C[2] (carbons in pale pink). Site-directed mutagenesis studies have shown that the protonated form of His-516 is largely responsible for the high reaction rate of oxygen with the reduced flavin in glucose oxidase (31).

Figures were selected by an automated process.