Cloning, Expression, and Characterization of a Chitinase from the Chitinolytic Bacterium Aeromonas hydrophila Strain SUWA-9
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The chitinolytic bacterium <I>Aeromonas hydrophila</I> strain SUWA-9, which was isolated from freshwater in Lake Suwa (Nagano Prefecture, Japan), produced several kinds of chitin-degrading enzymes. A gene coding for an endo-type chitinase (<I>chiA</I>) was isolated from SUWA-9. The <I>chiA</I> ORF encodes a polypeptide of 865 amino acid residues with a molecular mass of 91.6 kDa. The deduced amino acid sequence showed high similarity to those of bacterial chitinases classified into family 18 of glycosyl hydrolases. <I>chiA</I> was expressed in <I>Escherichia coli</I> and the recombinant chitinase (ChiA) was purified and examined. The enzyme hydrolyzed <I>N</I>-acetylchitooligomers from trimer to pentamer and produced monomer and dimer as a final product. It also reacted toward colloidal chitin and chitosan with a low degree of deacetylation. When cells of SUWA-9 were grown in the presence of colloidal chitin, a 60 kDa-truncated form of ChiA that had lost the C-terminal chitin-binding domain was secreted.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(10), 2437-2442, 2006-10-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry