7XMH

Crystal structure of a rice class IIIb chitinase, Oschib2

Summary for 7XMH

• Entry DOI: 10.2210/pdb7xmh/pdb
• Descriptor: Putative class III chitinase, 1,2-ETHANEDIOL, ACETATE ION, ... (4 entities in total)
• Functional Keywords: hydrolase, gh18 chitinase, family 8 pathogenesis-related protein
• Biological source: Oryza sativa (Asian cultivated rice)
• Total number of polymer chains: 1
• Total formula weight: 32490.93

Authors

Jun, T.,Tomoya, T.,Tomoyuki, N.,Takayuki, O. (deposition date: 2022-04-25, release date: 2023-05-03, Last modification date: 2023-11-29)

Primary citation

Tanaka, J.,Takashima, T.,Abe, N.,Fukamizo, T.,Numata, T.,Ohnuma, T.
Characterization of two rice GH18 chitinases belonging to family 8 of plant pathogenesis-related proteins.
Plant Sci., 326:111524-111524, 2023

PubMed Abstract: Two rice GH18 chitinases, Oschib1 and Oschib2, belonging to family 8 of plant pathogenesis-related proteins (PR proteins) were expressed, purified, and characterized. These enzymes, which have the structural features of class IIIb chitinases, preferentially cleaved the second glycosidic linkage from the non-reducing end of substrate chitin oligosaccharides as opposed to rice class IIIa enzymes, OsChib3a and OsChib3b, which mainly cleaved the fourth linkage from the non-reducing end of chitin hexasaccharide [(GlcNAc)]. Oschib1 and Oschiab2 inhibited the growth of Fusarium solani, but showed only a weak or no antifungal activity against Aspergillus niger and Trichoderma viride on the agar plates. Structural analysis of Oschib1 and Oschib2 revealed that these enzymes have two large loops extruded from the (β/α) TIM-barrel fold, which are absent in the structures of class IIIa chitinases. The differences in the cleavage site preferences toward chitin oligosaccharides between plant class IIIa and IIIb chitinases are likely attributed to the additional loop structures found in the IIIb enzymes. The class IIIb chitinases, Oschib1 and Oschib2, seem to play important roles for the effective hydrolysis of chitin oligosaccharides released from the cell wall of the pathogenic fungi by the cooperative actions with the extracellular chitinases in rice.

PubMed: 36328178
DOI: 10.1016/j.plantsci.2022.111524

Experimental method

X-RAY DIFFRACTION (1.18 Å)