Three extracellular chitinases in suspension-cultured rice cells elicited by N-acetylchitooligosaccharides.
In rice suspension culture, a large part (about 90% of total activity in the culture) of the chitinase activity was found in the medium. Two extracellular chitinases (which we named RCH-A and -B) were separated from the cell suspension by DEAE-cellulofine column chromatography. When cells were treated with N-acetylchitooligosaccharides (chitin oligosaccharides) for 3 days, extracellular chitinase activity increased about 3-fold over the control culture. After the treatment, another extracellular chitinase (named RCH-C) appeared in addition to increases in the levels of RCH-A and -B. Partial amino acid sequences of these enzymes indicated that RCH-A (33.5 kDa) and -B (34 kDa) were class Ib chitinases but RCH-C (27 kDa) was a class III chitinase. RCH-A and -B were capable of actively degrading water-insoluble chitin with high affinities, while RCH-C had less affinity for the substrate. However, when a water-soluble chitin derivative, 6-O-hydroxyethylchitin (glycolchitin) was used, RCH-C as well as RCH-A and -B degraded actively with a high affinity. A synergistic effect was observed when these three chitinases acted simultaneously in the hydrolysis of chitin.
Inui
H
H
Department of Agricultural Biochemistry and Biotechnology, Tottori University, Japan.
Yamaguchi
Y
Y
Ishigami
Y
Y
Kawaguchi
S
S
Yamada
T
T
Ihara
H
H
Hirano
S
S
D000595:Amino Acid Sequence; D002384:Catalysis; D002478:Cells, Cultured; D002688:Chitinases / Q000096:biosynthesis* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005110:Extracellular Space / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000494:pharmacology*; D012275:Oryza / Q000201:enzymology*
D009844:Oligosaccharides; D002688:Chitinases