PDBsum entry 3w4r

Hydrolase

PDB id: 3w4r

Contents

Protein chain

383 a.a.

Ligands

NAG ×2

Waters ×557

PDB id:

3w4r

Name:

Hydrolase

Title:

Crystal structure of an insect chitinase from the asian corn borer, ostrinia furnacalis

Structure:

Chitinase. Chain: a. Ec: 3.2.1.14

Source:

Ostrinia furnacalis. Asian corn borer. Organism_taxid: 93504

Resolution:

1.70Å R-factor: 0.147 R-free: 0.159

Authors:

L.Chen,T.Liu,Y.Zhou,X.Shen,Q.Yang

Key ref:

L.Chen et al. (2014). Structural characteristics of an insect group I chitinase, an enzyme indispensable to moulting. Acta Crystallogr D Biol Crystallogr, 70, 932-942. PubMed id: 24699639 DOI: 10.1107/S1399004713033841

Date:

10-Jan-13 Release date: 12-Feb-14

Protein chain

Q2V6H4  (Q2V6H4_OSTFU) -  Chitinase from Ostrinia furnacalis

Seq: 554 a.a.

Struc: 383 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.

DOI no: 10.1107/S1399004713033841

Acta Crystallogr D Biol Crystallogr 70:932-942 (2014)

PubMed id: 24699639

Structural characteristics of an insect group I chitinase, an enzyme indispensable to moulting.

L.Chen, T.Liu, Y.Zhou, Q.Chen, X.Shen, Q.Yang.

ABSTRACT

Insects possess a greater number of chitinases than any other organisms. This work is the first report of unliganded and oligosaccharide-complexed crystal structures of the insect chitinase OfChtI from Ostrinia furnacalis, which is essential to moulting. The obtained crystal structures were solved at resolutions between 1.7 and 2.2 Å. A structural comparison with other chitinases revealed that OfChtI contains a long substrate-binding cleft similar to the bacterial chitinase SmChiB from Serratia marcescens. However, unlike the exo-acting SmChiB, which has a blocked and tunnel-like cleft, OfChtI possesses an open and groove-like cleft. The complexed structure of the catalytic domain of OfChtI (OfChtI-CAD) with (GlcNAc)2/3 indicates that the reducing sugar at subsite -1 is in an energetically unfavoured `boat' conformation, a state that possibly exists just before the completion of catalysis. Because OfChtI is known to act from nonreducing ends, (GlcNAc)3 would be a hydrolysis product of (GlcNAc)6, suggesting that OfChtI possesses an endo enzymatic activity. Furthermore, a hydrophobic plane composed of four surface-exposed aromatic residues is adjacent to the entrance to the substrate-binding cleft. Mutations of these residues greatly impair the chitin-binding activity, indicating that this hydrophobic plane endows OfChtI-CAD with the ability to anchor chitin. This work reveals the unique structural characteristics of an insect chitinase.