5GPR

Crystal structure of chitinase-h from Ostrinia furnacalis

Summary for 5GPR

• Entry DOI: 10.2210/pdb5gpr/pdb
• Descriptor: Chitinase, 2-acetamido-2-deoxy-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: chitinase, ostrinia furnacalis, three dimensional structure, hydrolase
• Biological source: Ostrinia furnacalis (Asian corn borer)
• Total number of polymer chains: 1
• Total formula weight: 61512.07

Authors

Liu, T.,Zhou, Y.,Chen, L.,Yang, Q. (deposition date: 2016-08-04, release date: 2017-01-11, Last modification date: 2024-11-06)

Primary citation

Liu, T.,Chen, L.,Zhou, Y.,Jiang, X.,Duan, Y.,Yang, Q.
Structure, Catalysis, and Inhibition of OfChi-h, the Lepidoptera-exclusive Insect Chitinase.
J. Biol. Chem., 292:2080-2088, 2017

PubMed Abstract: Chitinase-h (Chi-h) is of special interest among insect chitinases due to its exclusive distribution in lepidopteran insects and high sequence identity with bacterial and baculovirus homologs. Here Chi-h, a Chi-h from , was investigated. Crystal structures of both Chi-h and its complex with chitoheptaose ((GlcN)) reveal that Chi-h possesses a long and asymmetric substrate binding cleft, which is a typical characteristics of a processive exo-chitinase. The structural comparison between Chi-h and its bacterial homolog ChiA uncovered two phenylalanine-to-tryptophan site variants in Chi-h at subsites +2 and possibly -7. The F232W/F396W double mutant endowed ChiA with higher hydrolytic activities toward insoluble substrates, such as insect cuticle, α-chitin, and chitin nanowhisker. An enzymatic assay demonstrated that Chi-h outperformed ChtI, an insect endo-chitinase, toward the insoluble substrates, but showed lower activity toward the soluble substrate ethylene glycol chitin. Furthermore, Chi-h was found to be inhibited by ,',″-trimethylglucosamine-,',″,″'-tetraacetylchitotetraose (TMG-(GlcNAc)), a substrate analog which can be degraded into TMG-(GlcNAc) Injection of TMG-(GlcNAc) into 5th-instar larvae led to severe defects in pupation. This work provides insights into a molting-indispensable insect chitinase that is phylogenetically closer to bacterial chitinases than insect chitinases.

PubMed: 28053084
DOI: 10.1074/jbc.M116.755330

Experimental method

X-RAY DIFFRACTION (3.23 Å)