The X‐ray structure of a chitinase from the pathogenic fungus <i>Coccidioides immitis</i>

Glycosidase and lectins both bind sugars, but only the glycosidases have catalytic activity. The glycosidases occur among 91 evolved protein families and Family 18 is one of the two chitinases (EC 3, 2.1.14) families. Interestingly, lectins are also in this evolutionary group of Family 18 glycosidase proteins. The proteins belonging to the enzymatically inactive class are referred to as, chitolectins and have a binding site that is highly similar to the catalytic Family 18 enzymes. We present a comparison of the recently obtained structures of two Family 18 chitolectins, MGP40 (Mohanty, Singh et al., 2003) and HumGP39 (Fusetti, Pijning et al., 2003;Houston, Anneliese et al., 2003) with glycosidases active site. We compare the sequence and the structure of these two Family 18 proteins. The difference between the active and inactive protein is a glutamic acid which acts as the essential acid/base residue for chitin cleavage is replaced with leucine or glutamine. Furthermore, mechanism for the interaction between the chitolectin and oligosaccharides were proposed.

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“…The structure is consistent with the (β/α) 8 barrel topology of the Family 18 glycosidase proteins . MGP40 is an Asn-linked glycoprotein itself.…”

Section: Mgp40supporting

confidence: 78%

Family 18 chitolectins: Comparison of MGP40 and HUMGP39

Ul-Haq

Dalal

Aronson

et al. 2007

Biochemical and Biophysical Research Communications

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“…In general, GH18 family chitinases bind their substrates in an extended recognition site, and VlCHI in this study contained the conserved substrate-binding and catalytic domains (SXGG and DXXDXDXE), as well as a conserved catalytic center containing 3 vital amino acid residues, Asp169, Trp170, and Glu171 . Several structures of fungal chitinase have been determined, such as chitinase from Aspergillus fumigatus (AfCHI) (PDB code: 1W9P) (Rao et al, 2005), Coccidioides immitis (cmChi) (PDB code: 1D2K) (Hollis et al, 2000), Yersinia entomophaga (YeCHI) (PDB code: 4A5Q) (Busby et al, 2012), and B. ochroleuca (also known as Clonostachys rosea) (BoChi1) (PDB code: 3G6M), and these structure were used to predict chitin binding, while biochemical assays were used to characterize chitinase in fungi. In this study, we utilized B. ochroleuca (BoChi1) (PDB code: 3G6M) as a template to generate a 3-D protein model of VlCHI using the SWISS-MODEL server.…”

Section: Discussionmentioning

confidence: 99%

Isolation, partial characterization, and cloning of an extracellular chitinase from the entomopathogenic fungus Verticillium lecanii

Xie

et al. 2015

Genet. Mol. Res.

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ABSTRACT. The entomopathogenic fungus Verticillium lecanii is a well-known biocontrol agent of fungal phytopathogens, as well as insect pests. A 42-kDa chitinase belonging to family 18 of the glycosyl hydrolases was isolated and partially characterized. Chitinase was purified using successive column chromatography on phenyl-sepharose, DEAE-sepharose, and CM-sepharose. The enzyme showed the highest activity at 40°C and pH 4.6. Enzyme activity was strongly activated in the presence of Mg 2+. The purified enzyme showed inhibitory activity of spore germination against several plant pathogens, particularly Fusarium moniliforme. The genomic DNA and cDNA sequences were resolved by polymerase chain reaction amplification and sequencing. Protein modeling and comparative investigation of different chitinase amino acids showed that chitinases are conserved in parasitic fungi.

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“…1 corresponding to the putative substrate binding site and catalytic domain of Vlchit1. The two signature sequences which lie along barrel strands 3 and 4 of the class 18 chitinases help form the active site cleft on the carboxyl end of the β-barrel and appear to be important both for stability of the fold and for catalytic activity (9,17).…”

Section: Modelling Of Vlchit1 Proteinmentioning

confidence: 99%

Isolation and characterization of a chitinase gene from entomopathogenic fungus Verticillium lecanii

Zhu¹,

Pan²,

Qiu³

et al. 2008

Braz. J. Microbiol.

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Entomopathogenic fungus Verticillium lecanii is a promising whitefly and aphid control agent. Chitinases secreted by this insect pathogen have considerable importance in the biological control of some insect pests. An endochitinase gene Vlchit1 from the fungus was cloned and overexpressed in Escherichia coli. The Vlchit1 gene not only contains an open reading frame (ORF) which encodes a protein of 423 amino acids (aa), but also is interrupted by three short introns. A homology modelling of Vlchit1 protein showed that the chitinase Vlchit1 has a (α/β)8 TIM barrel structure. Overexpression test and Enzymatic activity assay indicated that the Vlchit1 is a functional enzyme that can hydrolyze the chitin substrate, so the Vlchit1 gene can service as a useful gene source for genetic manipulation leading to strain improvement of entomopathogenic fungi or constructing new transgenic plants with resistance to various fungal and insects pests.

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The X‐ray structure of a chitinase from the pathogenic fungus Coccidioides immitis

Cited by 107 publications

References 36 publications

Family 18 chitolectins: Comparison of MGP40 and HUMGP39

Family 18 chitolectins: Comparison of MGP40 and HUMGP39

Isolation, partial characterization, and cloning of an extracellular chitinase from the entomopathogenic fungus Verticillium lecanii

Isolation and characterization of a chitinase gene from entomopathogenic fungus Verticillium lecanii

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