A molecular and biochemical analysis of the structure of the cyanogenic beta-glucosidase (linamarase) from cassava (Manihot esculenta Cranz).
The cyanogenic beta-glucosidase (linamarase) of cassava is responsible for the first step in the sequential break-down of two related cyanoglucosides. Hydrolysis of these cyanoglucosides occurs following tissue damage and leads to the production of hydrocyanic acid. This mechanism is widely regarded as a defense mechanism against predation. A linamarase cDNA clone (pCAS5) was isolated from a cotyledon cDNA library using a white clover beta-glucosidase heterologous probe. The nucleotide and derived amino acid sequence is reported and five putative N-asparagine glycosylation sites are identified. Concanavalin A affinity chromatography and endoglycosidase H digestion demonstrate that linamarase from cassava is glycosylated, having high-mannose-type N-asparagine-linked oligosaccharides. Consistent with this structure and the extracellular location of the active enzyme is the identification of an N-terminal signal peptide on the deduced amino acid sequence of pCAS5.
Hughes
M A
MA
Department of Biochemistry and Genetics, The University, Newcastle upon Tyne, United Kingdom.
Brown
K
K
Pancoro
A
A
Murray
B S
BS
Oxtoby
E
E
Hughes
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D006596:Hexosaminidases; D007700:Kinetics; D002365:Manihot / Q000201:enzymology*; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D001617:beta-Glucosidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
D004247:DNA; D006596:Hexosaminidases; C021514:cyanogenic beta-glucosidase; D001617:beta-Glucosidase