PDBsum entry 1hvq

Hydrolase

PDB id: 1hvq

Contents

Protein chain

273 a.a. *

Ligands

NAG-NAG-NAG

Waters ×204

* Residue conservation analysis

PDB id:

1hvq

Name:

Hydrolase

Title:

Crystal structures of hevamine, a plant defence protein with chitinase and lysozyme activity, and its complex with an inhibitor

Structure:

Hevamine a. Chain: a. Other_details: plant endochitinase/lysozyme

Source:

Hevea brasiliensis. Organism_taxid: 3981. Tissue: latex

Resolution:

2.20Å R-factor: 0.144 R-free: 0.244

Authors:

A.C.Terwisscha Van Scheltinga,K.H.Kalk,J.J.Beintema,B.W.Dijkstra

Key ref:

A.C.Terwisscha van Scheltinga et al. (1994). Crystal structures of hevamine, a plant defence protein with chitinase and lysozyme activity, and its complex with an inhibitor. Structure, 2, 1181-1189. PubMed id: 7704528 DOI: 10.1016/S0969-2126(94)00120-0

Date:

13-Oct-94 Release date: 02-Dec-95

Protein chain

P23472  (CHLY_HEVBR) -  Hevamine-A from Hevea brasiliensis

Seq: 311 a.a.

Struc: 273 a.a.

Enzyme reactions

• Enzyme class 1: E.C.3.2.1.14 - chitinase.
• Reaction: Hydrolysis of the 1,4-beta-linkages of N-acetyl-D-glucosamine polymers of chitin.
• Enzyme class 2: E.C.3.2.1.17 - lysozyme.
• Reaction: Hydrolysis of the 1,4-beta-linkages between N-acetyl-D-glucosamine and N-acetylmuramic acid in peptidoglycan heteropolymers of the prokaryotes cell walls.

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

DOI no: 10.1016/S0969-2126(94)00120-0

Structure 2:1181-1189 (1994)

PubMed id: 7704528

Crystal structures of hevamine, a plant defence protein with chitinase and lysozyme activity, and its complex with an inhibitor.

A.C.Terwisscha van Scheltinga, K.H.Kalk, J.J.Beintema, B.W.Dijkstra.

ABSTRACT

BACKGROUND: Hevamine is a member of one of several families of plant chitinases and lysozymes that are important for plant defence against pathogenic bacteria and fungi. The enzyme can hydrolyze the linear polysaccharide chains of chitin and peptidoglycan. A full understanding of the structure/function relationships of chitinases might facilitate the production of transgenic plants with increased resistance towards a wide range of pathogens. RESULTS: The crystal structure of hevamine has been determined to a resolution of 2.2 A, and refined to an R-factor of 0.169. The enzyme possesses a (beta alpha)8-barrel fold. An inhibitor binding study shows that the substrate-binding cleft is located at the carboxy-terminal end of the beta-barrel, near the conserved Glu127. Glu127 is in a position to act as the catalytic proton donor, but no residue that might stabilize a positively charged oxocarbonium ion intermediate was found. A likely mechanism of substrate hydrolysis is by direct attack of a water molecule on the C1 atom of the scissile bond, resulting in inversion of the configuration at C1. CONCLUSIONS: The structure of hevamine shows a completely new lysozyme/chitinase fold and represents a new class of polysaccharide-hydrolyzing (beta alpha)8-barrel enzymes. Because the residues conserved in the family to which hevamine belongs are important for maintaining the structure of the (beta alpha)8-barrel, all members of the family, including fungal, bacterial and insect chitinases, are likely to share this architecture. The crystal structure obtained provides a basis for protein engineering studies in this family of chitinases.

Selected figure(s)

Figure 4.
Figure 4. Schematic drawing of the hydrogen-bonding pattern of the consensus regions. The highly conserved side chains and the hydrogen bonds that they make within the consensus regions are shown in red, the rest of the consensus regions are shown in blue. Hydrogen bonds made with residues outside the consensus regions are shown in green. Protonation of the side chains is shown to be most probable at pH 4.0, the pH optimum of hevamine. Figure 4. Schematic drawing of the hydrogen-bonding pattern of the consensus regions. The highly conserved side chains and the hydrogen bonds that they make within the consensus regions are shown in red, the rest of the consensus regions are shown in blue. Hydrogen bonds made with residues outside the consensus regions are shown in green. Protonation of the side chains is shown to be most probable at pH 4.0, the pH optimum of hevamine.

Figure 6.
Figure 6. Stereo figure showing the van der Waals interactions between hevamine and tri-NAG. Figure 6. Stereo figure showing the van der Waals interactions between hevamine and tri-NAG.

The above figures are reprinted by permission from Cell Press: Structure (1994, 2, 1181-1189) copyright 1994.

Figures were selected by an automated process.