Open AccessA novel type of family 19 chitinase from Aeromonas sp. No.10S‐24
Author(s) -
Ueda Mitsuhiro,
Kojima Miki,
Yoshikawa Tomoye,
Mitsuda Norio,
Araki Keiichi,
Kawaguchi Takashi,
Miyatake Kazutaka,
Arai Motoo,
Fukamizo Tamo
Publication year - 2003
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2003.03624.x
Subject(s) - chitinase , glycosidic bond , glycoside hydrolase , biochemistry , enzyme , chemistry , aeromonas , chitin , peptide sequence , stereochemistry , amino acid , escherichia coli , biology , gene , bacteria , genetics , chitosan
A family 19 chitinase gene from Aeromonas sp. No.10S‐24 was cloned, sequenced, and expressed in Escherichia coli . From the deduced amino acid sequence, the enzyme was found to possess two repeated N‐terminal chitin‐binding domains, which are separated by two proline‐threonine rich linkers. The calculated molecular mass was 70 391 Da. The catalytic domain is homologous to those of plant family 19 chitinases by about 47%. The enzyme produced α‐anomer by hydrolyzing β‐1,4‐glycosidic linkage of the substrate, indicating that the enzyme catalyzes the hydrolysis through an inverting mechanism. When N ‐acetylglucosamine hexasaccharide [(GlcNAc) 6 ] was hydrolyzed by the chitinase, the second glycosidic linkage from the nonreducing end was predominantly split producing (GlcNAc) 2 and (GlcNAc) 4 . The evidence from this work suggested that the subsite structure of the enzyme was (−2)(−1)(+1)(+2)(+3)(+4), whereas most of plant family 19 chitinases have a subsite structure (−3)(−2)(−1)(+1)(+2)(+3). Thus, the Aeromonas enzyme was found to be a novel type of family 19 chitinase in its structural and functional properties.