PDBsum entry 1qqj

Hydrolase

PDB id: 1qqj

Contents

Protein chains

416 a.a. *

Ligands

ACT ×2

CAC ×2

Metals

_CA ×2

Waters ×894

* Residue conservation analysis

PDB id:

1qqj

Name:

Hydrolase

Title:

Crystal structure of mouse fumarylacetoacetate hydrolase refined at 1.55 angstrom resolution

Structure:

Fumarylacetoacetate hydrolase. Chain: a, b. Synonym: betadiketonase, faa. Engineered: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

1.55Å R-factor: 0.183 R-free: 0.211

Authors:

D.E.Timm,H.A.Mueller,P.Bhanumoorthy,J.M.Harp,G.J.Bunick

Key ref:

D.E.Timm et al. (1999). Crystal structure and mechanism of a carbon-carbon bond hydrolase. Structure, 7, 1023-1033. PubMed id: 10508789 DOI: 10.1016/S0969-2126(99)80170-1

Date:

07-Jun-99 Release date: 07-Jun-00

Protein chains

P35505  (FAAA_MOUSE) -  Fumarylacetoacetase from Mus musculus

Seq: 419 a.a.

Struc: 416 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.7.1.2 - fumarylacetoacetase.
• Reaction: 4-fumarylacetoacetate + H2O = acetoacetate + fumarate + H⁺

4-fumarylacetoacetate + H2O = acetoacetate (Bound ligand (Het Group name = ACT) matches with 57.14% similarity) + fumarate + H(+)

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

reference

DOI no: 10.1016/S0969-2126(99)80170-1

Structure 7:1023-1033 (1999)

PubMed id: 10508789

Crystal structure and mechanism of a carbon-carbon bond hydrolase.

D.E.Timm, H.A.Mueller, P.Bhanumoorthy, J.M.Harp, G.J.Bunick.

ABSTRACT

BACKGROUND: Fumarylacetoacetate hydrolase (FAH) catalyzes the final step of tyrosine and phenylalanine catabolism, the hydrolytic cleavage of a carbon-carbon bond in fumarylacetoacetate, to yield fumarate and acetoacetate. FAH has no known sequence homologs and functions by an unknown mechanism. Carbon-carbon hydrolysis reactions are essential for the human metabolism of aromatic amino acids. FAH deficiency causes the fatal metabolic disease hereditary tyrosinemia type I. Carbon-carbon bond hydrolysis is also important in the microbial metabolism of aromatic compounds as part of the global carbon cycle. RESULTS: The FAH crystal structure has been determined by rapid, automated analysis of multiwavelength anomalous diffraction data. The FAH polypeptide folds into a 120-residue N-terminal domain and a 300-residue C-terminal domain. The C-terminal domain defines an unusual beta-strand topology and a novel 'mixed beta-sandwich roll' structure. The structure of FAH complexed with its physiological products was also determined. This structure reveals fumarate binding near the entrance to the active site and acetoacetate binding to an octahedrally coordinated calcium ion located in close proximity to a Glu-His dyad. CONCLUSIONS: FAH represents the first structure of a hydrolase that acts specifically on carbon-carbon bonds. FAH also defines a new class of metalloenzymes characterized by a unique alpha/beta fold. A mechanism involving a Glu-His-water catalytic triad is suggested based on structural observations, sequence conservation and mutational analysis. The histidine imidazole group is proposed to function as a general base. The Ca(2+) is proposed to function in binding substrate, activating the nucleophile and stabilizing a carbanion leaving group. An oxyanion hole formed from sidechains is proposed to stabilize a tetrahedral alkoxide transition state. The proton transferred to the carbanion leaving group is proposed to originate from a lysine sidechain. The results also reveal the molecular basis for mutations causing the hereditary tyrosinemia type 1.

Selected figure(s)

Figure 2.
Figure 2. FAH structure, topology and HT1-associated mutations. (a) A stereo ribbon diagram illustrating the FAH subunit structure and position of point mutations causing hereditary tyrosinemia type I is shown. The N-terminal domain is located at the bottom of the figure. The mixed b-sandwich roll structure is centrally located in the figure. Helices are colored red; b strands are colored in shades of blue corresponding to the b sheet they form; the positions of point mutations are represented by green spheres; a calcium ion is colored yellow; acetate carbon and oxygen atoms are respectively colored orange and red (top of figure). (b) A topology diagram of the novel FAH b-strand arrangement is shown. b Strands are numbered in red according to their sequential occurrence in the polypeptide chain; residue numbering is in black. Sheets A, B and C are respectively colored in dark, light and medium shades of blue, as in (a). a Helices are represented by red rectangles. Figure 2, Figure 3 and Figure 4 and Figure 6b were generated using MOLSCRIPT [40].

The above figure is reprinted by permission from Cell Press: Structure (1999, 7, 1023-1033) copyright 1999.

Figure was selected by an automated process.