PDBsum entry: 1lq0

Hydrolase

PDB id: 1lq0

Contents

Protein chain

365 a.a. *

Waters ×134

* Residue conservation analysis

PDB id:

1lq0

Name:

Hydrolase

Title:

Crystal structure of human chitotriosidase at 2.2 angstrom resolution

Structure:

Chitotriosidase. Chain: a. Fragment: residues 22-286. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: cricetulus griseus. Expression_system_taxid: 10029.

Resolution:

2.20Å R-factor: 0.212 R-free: 0.248

Authors:

F.Fusetti,H.J.Rozeboom,B.W.Dijkstra

Key ref:

F.Fusetti et al. (2002). Structure of human chitotriosidase. Implications for specific inhibitor design and function of mammalian chitinase-like lectins. J Biol Chem, 277, 25537-25544. PubMed id: 11960986 DOI: 10.1074/jbc.M201636200

Date:

08-May-02 Release date: 29-Jul-03

Protein chain

Q13231  (CHIT1_HUMAN) -  Chitotriosidase-1

Seq: 466 a.a.

Struc: 365 a.a.

Enzyme reactions

• Enzyme class: E.C.3.2.1.14 - Chitinase.
• Reaction: Hydrolysis of the 1,4-beta-linkages of N-acetyl-D-glucosamine polymers of chitin.

 Gene Ontology (GO) functional annotation 

• Biological process: carbohydrate metabolic process (2 terms)
• Biochemical function: catalytic activity (4 terms)

DOI no: 10.1074/jbc.M201636200

J Biol Chem 277:25537-25544 (2002)

PubMed id: 11960986

Structure of human chitotriosidase. Implications for specific inhibitor design and function of mammalian chitinase-like lectins.

F.Fusetti, H.von Moeller, D.Houston, H.J.Rozeboom, B.W.Dijkstra, R.G.Boot, J.M.Aerts, D.M.van Aalten.

ABSTRACT

Chitin hydrolases have been identified in a variety of organisms ranging from bacteria to eukaryotes. They have been proposed to be possible targets for the design of novel chemotherapeutics against human pathogens such as fungi and protozoan parasites as mammals were not thought to possess chitin-processing enzymes. Recently, a human chitotriosidase was described as a marker for Gaucher disease with plasma levels of the enzyme elevated up to 2 orders of magnitude. The chitotriosidase was shown to be active against colloidal chitin and is inhibited by the family 18 chitinase inhibitor allosamidin. Here, the crystal structure of the human chitotriosidase and complexes with a chitooligosaccharide and allosamidin are described. The structures reveal an elongated active site cleft, compatible with the binding of long chitin polymers, and explain the inactivation of the enzyme through an inherited genetic deficiency. Comparison with YM1 and HCgp-39 shows how the chitinase has evolved into these mammalian lectins by the mutation of key residues in the active site, tuning the substrate binding specificity. The soaking experiments with allosamidin and chitooligosaccharides give insight into ligand binding properties and allow the evaluation of differential binding and design of species-selective chitinase inhibitors.

Selected figure(s)

Figure 1.
Fig. 1. Overview of chitotriosidase structure and comparison with other chitinases. A, stereo image of the final human chitotriosidase structure. The backbone is shown as a gray ribbon. The / domain is colored blue. Residues 344-372, which are deleted in the inherited mutated form of the enzyme, are colored green. Asp-136, Asp-138, and Glu-140 are shown as a sticks model with carbons colored yellow. Solvent-exposed aromatic side chains lining the active site cleft are shown as purple sticks. NAG[2], as seen in the complex (Table I), is shown in a sticks representation with orange carbon atoms. B, stereo image of the active site. The chitotriosidase backbone is shown as a gray ribbon. Solvent-exposed aromatics and residues interacting with NAG[2] are shown as sticks with carbons colored green for the apo structure and carbons colored purple for the chitotriosidase-NAG[2] complex. A simulated-annealing F[o] F[c], [calc] map for NAG[2] as observed in the chitotriosidase-NAG[2] complex is shown in blue, contoured at 3 . NAG[2] is shown in a sticks representation with orange carbon atoms. C, overall comparison with other chitinases. Molecular surfaces (calculated with PyMOL) are shown for currently known complexes of chitinases with chitooligosaccharides: hevamine with NAG[3] (31), ChiA with NAG [8] (32), ChiB with NAG[5] (29), and the human chitotriosidase with a model of NAG[9]. The TIM barrel core of the enzymes is orientated as in panel A. The catalytic glutamic acid is colored red, and exposed aromatic side chains lining the active site cleft are colored blue. The chitooligosaccharides are shown as sticks with green carbons.

Figure 3.
Fig. 3. Comparison of active site details and interaction with allosamidin. In A, the substrate binding pockets of the human chitotriosidase and YM1 are compared. Protein backbones are represented by a gray ribbon. A model of NAG[9], in equivalent position to that in Fig. 1, is shown as a sticks drawing with orange carbons. Side chains in the active site cleft are shown as sticks with green carbons, except for the catalytic glutamic acid, which is shown with yellow carbons. For YM1, non-conserved residues are shown with magenta carbons. In B, the interaction with allosamidin is compared for the chitotriosidase complex described here and the published C. immitis CTS1 chitinase complex (28). For both complexes, the enzyme backbone is shown as a gray ribbons model in stereo, and allosamidin is shown in a sticks representation with carbons colored orange. For the chitotriosidase, side chains contacting the inhibitor (defined as F[c], [calc] map (i.e. before the inclusion of any allosamidin model) is shown in magenta, contoured at 2.25 . For the CTS1-allosamidin complex, equivalent side chains are shown.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 25537-25544) copyright 2002.

Figures were selected by an automated process.