A modular family 19 chitinase found in the prokaryotic organism Streptomyces griseus HUT 6037.
The specificity of chitinase C-1 of Streptomyces griseus HUT 6037 for the hydrolysis of the beta-1,4-glycosidic linkages in partially acetylated chitosan is different from that of other microbial chitinases. In order to study the primary structure of this unique chitinase, the chiC gene specifying chitinase C-1 was cloned and its nucleotide sequence was determined. The gene encodes a polypeptide of 294 amino acids with a calculated size of 31.4 kDa. Comparison of the amino acid sequence of the deduced polypeptide with that of other proteins revealed a C-terminal catalytic domain displaying considerable sequence similarity to the catalytic domain of plant class I, II, and IV chitinases which form glycosyl hydrolase family 19. The N-terminal domain of the deduced polypeptide exhibits sequence similarity to substrate-binding domains of several microbial chitinases and cellulases but not to the chitin-binding domains of plant chitinases. The previously purified chitinase C-1 from S. griseus is suggested to be generated by proteolytic removal of the N-terminal chitin-binding domain and corresponds to the catalytic domain of the chitinase encoded by the chiC gene. High-performance liquid chromatography analysis of the hydrolysis products from N-acetyl chitotetraose revealed that chitinase C-1 catalyzes hydrolysis of the glycosidic bond with inversion of the anomeric configuration, in agreement with the previously reported inverting mechanism of plant class I chitinases. This is the first report of a family 19 chitinase found in an organism other than higher plants.
Ohno
T
T
Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, Japan.
Armand
S
S
Hata
T
T
Nikaidou
N
N
Henrissat
B
B
Mitsutomi
M
M
Watanabe
T
T
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004926:Escherichia coli; D006868:Hydrolysis; D008969:Molecular Sequence Data; D011387:Prokaryotic Cells; D017386:Sequence Homology, Amino Acid; D013305:Streptomyces griseus / Q000201:enzymology* / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D002686:Chitin; D002688:Chitinases; C101644:chitinase C-1