What question did this study set out to answer?

The research aims to characterize MoChia1, a glycoside hydrolase from Magnaporthe oryzae, and its role in chitin oligosaccharide hydrolysis.

April 19, 2026Open Access

MoChia1 is a GH18 Reducing-End GlcNAc–Releasing Chitin Oligosaccharide Hydrolase from the Rice Blast Fungus Magnaporthe oryzae

Key Points

The research aims to characterize MoChia1, a glycoside hydrolase from Magnaporthe oryzae, and its role in chitin oligosaccharide hydrolysis.
Identified MoChia1 enzyme from Magnaporthe oryzae.
Analyzed hydrolytic activity on chitin oligosaccharides using HPLC.
Assessed substrate specificity and anomeric selectivity.
Evaluated the inhibitory effects of allosamidin on MoChia1.
MoChia1 hydrolyzed chitin oligosaccharides with a minimum polymerization degree of 3.
It specifically recognized the -anomer of substrates and cleaved at the reducing end.
Allosamidin inhibited MoChia1 activity with an IC50 of 54.4 ± 6.91 µM, suggesting its potential as a pesticide.

Abstract

MoChia1, a family 18 glycoside hydrolase from the rice blast fungus Magnaporthe oryzae, was identified as an enzyme that binds chitin oligosaccharide elicitor to suppress the chitin-induced rice immune response.It hydrolyzed chitin oligosaccharides with a degree of polymerization of at least 3 (GlcNAc)n (n3) in an exo-splitting manner with anomeric retention.HPLC analysis of (GlcNAc)n cleavage by MoChia1 revealed that it specifically recognizes the -anomer of the substrate at the +1 subsite and cleaves the terminal glycosidic linkage at the reducing end.It also hydrolyzed the hetero-chitotriose GlcN-GlcNAc-GlcNAc, producing GlcN-GlcNAc and GlcNAc, but not GlcN-GlcN-GlcNAc, indicating the requirement of the N-acetyl group at the -1 subsite for the hydrolytic reaction.MoChia1 released p-nitrophenol from pNP-Furthermore, it hydrolyzed the chitotriose derivatives with a modified GlcNAc residue on the reducing end, (GlcNAc)2-G, 4-O--di-N-acetylchitobiosyl-2-acetamido-2-deoxy-2,3-anhydroglucopyranose and (GlcNAc)2-L, 4-O--di-N-acetylchitobiosyl-2-acetamido-2-deoxy-2,3-anhydro-glucono--lactone, to (GlcNAc)2 and the modified GlcNAc, respectively.However, it did not hydrolyze 4-O--di-N-acetylchitobiosyl moranoline (GlcNAc)2-M, reduced chitotriose (chitotriitol), and -(GlcNAc)2 fluoride (-(GlcNAc)2-F.MoChia1 did not bind to chitin and barely hydrolyzed the polymeric substrate, glycol chitin.Taken together, we concluded that MoChia1 is a GH18 reducing-end GlcNAc-releasing chitin oligosaccharide hydrolase with the -anomer selectivity.Allosamidin, a potent inhibitor of GH18 chitinases, was found to bind to MoChia1 and inhibit its hydrolytic activity with an IC50 of 54.4 6.91 M, indicating that allosamidin may be a potential candidate for a pesticide to prevent rice blast infection by inhibiting the chitinase J o u r n a l P r e -p r o o f activity of MoChia1.Abbreviations -(GlcNAc)2-F, -(GlcNAc)2 fluoride; BSA, bovine serum albumin; (GlcNAc)n, -1,4linked oligosaccharide of GlcNAc with a polymerization degree of n; GlcN, Dglucosamine; GlcNAc, N-acetyl-D-glucosamine; GH, glycoside hydrolase; (GlcNAc)2-G, 4-O--di-N-acetylchitobiosyl-2-acetamido-2-deoxy-2,3-anhydro-glucopyranose; (GlcNAc)2-L, 4-O--di-N-acetylchitobiosyl-2-acetamido-2-deoxy-2,3-anhydro-glucono-lactone; (GlcNAc)2-M,

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