Heterologous expression and characterization of a novel chitin deacetylase, CDA3, from the mushroom Coprinopsis cinerea.

The chitin deacetylase CDA3 from C. cinerea deacetylated chitin-oligosaccharides with dp ≥ 2. Since CDA3 firstly removed the intermediate acetyl group of (GlcNAc), it was an endo-acting deacetylase. Different from previously reported deacetylation modes, CDA3 deacetylated chitinbiose at either the reducing end or the nonreducing end; CDA3 deacetylated chitintriose at any subsite including the end and the intermediate; CDA3 further removed acetyl groups at any subsite, the intermediate, nonreducing and reducing end of chitintetraose after removal of the first intermediate acetyl group. 3D structural analysis showed that CDA3 has aromatic amino acids distributing at both the +1 and -1 subsites of the catalytic site, which may be responsible for its distinctive deacetylation mode. Furthermore, CDA3 was active on crystalline chitin, its deacetylation activity increased with the DA decreases of chitinous substrates and showed a higher activity towards the cell wall of the basal stipe with the higher molar ratio of GlcN/GlcNAc than that of the apical stipe with the lower molar ratio of GlcN/GlcNAc. CDA3 with distinctive deacetylation mode and activity indicates its function during the maturation of the fruiting bodies of C. cinerea and a potential for preparation of mushroom chitosan for application in the food, cosmetics, and pharmaceutical industries.