3WL0

Crystal structure of Ostrinia furnacalis Group I chitinase catalytic domain E148A mutant in complex with a(GlcNAc)2

Summary for 3WL0

• Entry DOI: 10.2210/pdb3wl0/pdb
• Related: 3W4R 3WKZ 3WL1
• Descriptor: Chitinase, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (4 entities in total)
• Functional Keywords: glycosyl hydrolase, insect, ostrinia furnacalis, hydrolase
• Biological source: Ostrinia furnacalis (Asian corn borer)
• Total number of polymer chains: 1
• Total formula weight: 45804.39

Authors

Chen, L.,Liu, T.,Zhou, Y.,Chen, Q.,Shen, X.,Yang, Q. (deposition date: 2013-11-05, release date: 2014-04-09, Last modification date: 2024-10-16)

Primary citation

Chen, L.,Liu, T.,Zhou, Y.,Chen, Q.,Shen, X.,Yang, Q.
Structural characteristics of an insect group I chitinase, an enzyme indispensable to moulting.
Acta Crystallogr.,Sect.D, 70:932-942, 2014

PubMed 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.

PubMed: 24699639
DOI: 10.1107/S1399004713033841

Experimental method

X-RAY DIFFRACTION (2.204 Å)