title: Structure, Catalysis, and Inhibition ofOfChi-h, the Lepidoptera-exclusive Insect Chitinase.
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. HereOfChi-h, a Chi-h fromOstrinia furnacalis, was investigated. Crystal structures of bothOfChi-h and its complex with chitoheptaose ((GlcN)7) reveal thatOfChi-h possesses a long and asymmetric substrate binding cleft, which is a typical characteristics of a processive exo-chitinase. The structural comparison betweenOfChi-h and its bacterial homologSmChiA uncovered two phenylalanine-to-tryptophan site variants inOfChi-h at subsites +2 and possibly -7. The F232W/F396W double mutant endowedSmChiA with higher hydrolytic activities toward insoluble substrates, such as insect cuticle, α-chitin, and chitin nanowhisker. An enzymatic assay demonstrated thatOfChi-h outperformedOfChtI, an insect endo-chitinase, toward the insoluble substrates, but showed lower activity toward the soluble substrate ethylene glycol chitin. Furthermore,OfChi-h was found to be inhibited byN,N',N″-trimethylglucosamine-N,N',N″,N″'-tetraacetylchitotetraose (TMG-(GlcNAc)4), a substrate analog which can be degraded into TMG-(GlcNAc)1-2Injection of TMG-(GlcNAc)4into 5th-instarO. furnacalislarvae 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.
authors.affiliation: From the State Key Laboratory of Fine Chemical Engineering, School of Life Science and Biotechnology and School of Software, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China and.
authors.forename: Tian
authors.initials: T
authors.lastname: Liu
authors.affiliation: From the State Key Laboratory of Fine Chemical Engineering, School of Life Science and Biotechnology and School of Software, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China and.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: From the State Key Laboratory of Fine Chemical Engineering, School of Life Science and Biotechnology and School of Software, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China and.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: From the State Key Laboratory of Fine Chemical Engineering, School of Life Science and Biotechnology and School of Software, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China and.
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
authors.affiliation: From the State Key Laboratory of Fine Chemical Engineering, School of Life Science and Biotechnology and School of Software, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China and.
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Duan
authors.affiliation: From the State Key Laboratory of Fine Chemical Engineering, School of Life Science and Biotechnology and School of Software, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China and qingyang@dlut.edu.cn.|Institute of Plant Protection, Chinese Academy of Agricultural Sciences, 2 West Yuanmingyuan Road, Beijing 100193, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
mesh_terms: D000818:Animals; D002384:Catalysis; D002688:Chitinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007915:Lepidoptera / Q000201:enzymology*; D011487:Protein Conformation; D059748:Proteolysis; D013379:Substrate Specificity
chemical_list: D002688:Chitinases
keywords: chitin; chitinase; crystal structure; inhibitor; insect; molting