PDBsum entry 2isv

Lyase

PDB id: 2isv

Contents

Protein chains

298 a.a. *

Ligands

PGH ×2

Metals

_ZN ×2

Waters ×368

* Residue conservation analysis

PDB id:

2isv

Name:

Lyase

Title:

Structure of giardia fructose-1,6-biphosphate aldolase in complex with phosphoglycolohydroxamate

Structure:

Putative fructose-1,6-bisphosphate aldolase. Chain: a, b. Engineered: yes

Source:

Giardia intestinalis. Organism_taxid: 5741. Strain: wb. Gene: ald. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

2.30Å R-factor: 0.199 R-free: 0.261

Authors:

A.Galkin,O.Herzberg

Key ref:

A.Galkin et al. (2007). Characterization, kinetics, and crystal structures of fructose-1,6-bisphosphate aldolase from the human parasite, Giardia lamblia. J Biol Chem, 282, 4859-4867. PubMed id: 17166851 DOI: 10.1074/jbc.M609534200

Date:

18-Oct-06 Release date: 12-Dec-06

Protein chains

A8B2U2  (A8B2U2_GIAIC) -  Fructose-bisphosphate aldolase from Giardia intestinalis (strain ATCC 50803 / WB clone C6)

Seq: 323 a.a.

Struc: 298 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.4.1.2.13 - fructose-bisphosphate aldolase.
• Reaction: beta-D-fructose 1,6-bisphosphate = D-glyceraldehyde 3-phosphate + dihydroxyacetone phosphate

beta-D-fructose 1,6-bisphosphate = D-glyceraldehyde 3-phosphate (Bound ligand (Het Group name = PGH) matches with 66.67% similarity) + dihydroxyacetone phosphate

• Cofactor: Zn(2+)

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

reference

DOI no: 10.1074/jbc.M609534200

J Biol Chem 282:4859-4867 (2007)

PubMed id: 17166851

Characterization, kinetics, and crystal structures of fructose-1,6-bisphosphate aldolase from the human parasite, Giardia lamblia.

A.Galkin, L.Kulakova, E.Melamud, L.Li, C.Wu, P.Mariano, D.Dunaway-Mariano, T.E.Nash, O.Herzberg.

ABSTRACT

Class I and class II fructose-1,6-bisphosphate aldolases (FBPA), glycolytic pathway enzymes, exhibit no amino acid sequence homology and utilize two different catalytic mechanisms. The mammalian class I FBPA employs a Schiff base mechanism, whereas the human parasitic protozoan Giardia lamblia class II FBPA is a zinc-dependent enzyme. In this study, we have explored the potential exploitation of the Giardia FBPA as a drug target. First, synthesis of FBPA was demonstrated in Giardia trophozoites by using an antibody-based fluorescence assay. Second, inhibition of FBPA gene transcription in Giardia trophozoites suggested that the enzyme is necessary for the survival of the organism under optimal laboratory growth conditions. Third, two crystal structures of FBPA in complex with the transition state analog phosphoglycolohydroxamate (PGH) show that the enzyme is homodimeric and that its active site contains a zinc ion. In one crystal form, each subunit contains PGH, which is coordinated to the zinc ion through the hydroxamic acid hydroxyl and carbonyl oxygen atoms. The second crystal form contains PGH only in one subunit and the active site of the second subunit is unoccupied. Inspection of the two states of the enzyme revealed that it undergoes a conformational transition upon ligand binding. The enzyme cleaves d-fructose-1,6-bisphosphate but not d-tagatose-1,6-bisphosphate, which is a tight binding competitive inhibitor. The essential role of the active site residue Asp-83 in catalysis was demonstrated by amino acid replacement. Determinants of catalysis and substrate recognition, derived from comparison of the G. lamblia FBPA structure with Escherichia coli FBPA and with a closely related enzyme, E. coli tagatose-1,6-bisphosphate aldolase (TBPA), are described.

Selected figure(s)

Figure 1.
FIGURE 1. A, reaction catalyzed by FBPA. B, FBPA inhibitor, PGH, mimicking the DHAP ene-diolate transition-state intermediate.

Figure 2.
FIGURE 2. The catalytic mechanism of class I and class II FBPA.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2007, 282, 4859-4867) copyright 2007.

Figures were selected by an automated process.