AUTHOR=Wang Chengyong , Chen Xueman , Zhou Ning , Chen Yan , Zhang Alei , Chen Kequan , Ouyang Pingkai 

TITLE=Property and Function of a Novel Chitinase Containing Dual Catalytic Domains Capable of Converting Chitin Into N-Acetyl-D-Glucosamine

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.790301

DOI=10.3389/fmicb.2022.790301

ISSN=1664-302X

ABSTRACT=<p>A novel multifunctional chitinase (<italic>Cm</italic>Chi3)-encoding gene was cloned from <italic>Chitinolyticbacter meiyuanensis</italic> and actively expressed in <italic>Escherichia coli</italic>. Sequence analysis showed that <italic>Cm</italic>Chi3 contains two glycoside hydrolase family 18 (GH18) catalytic domains and exhibited low identity with well-characterized chitinases. The optimum pH and temperature of purified recombinant <italic>Cm</italic>Chi3 were 6.0 and 50°C, respectively. <italic>Cm</italic>Chi3 exhibited strict substrate specificity of 4.1 U/mg toward colloidal chitin (CC) and hydrolyzed it to yield <italic>N</italic>-acetyl-D-glucosamine (GlcNAc) as the sole end product. An analysis of the hydrolysis products toward <italic>N</italic>-acetyl chitooligosaccharides (<italic>N</italic>-acetyl COSs) and CC substrates revealed that <italic>Cm</italic>Chi3 exhibits endochitinase, <italic>N</italic>-acetyl-β-d-glucosaminidase (NAGase), and transglycosylase (TGase) activities. Further studies revealed that the N-terminal catalytic domain of <italic>Cm</italic>Chi3 exhibited endo-acting and NAGase activities, while the C-terminal catalytic domain showed exo-acting and TGase activities. The hydrolytic properties and favorable environmental adaptations indicate that <italic>Cm</italic>Chi3 holds potential for commercial GlcNAc production from chitin.</p>