Characterization and evolution of a myrosinase from the cabbage aphid Brevicoryne brassicae

The aphid myrosinase gene has been elucidated using Rapid Amplification of cDNA Ends—PCR. Sequencing has shown that aphid myrosinase has significant sequence similarity (35%) to plant myrosinases and other members of glycosyl hydrolase family 1 (GHF1). The residues acting as proton donor and nucleop...

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Bibliographic Details
Published in:Insect biochemistry and molecular biology 2002-03, Vol.32 (3), p.275-284
Main Authors: Jones, A.M.E., Winge, P., Bones, A.M., Cole, R., Rossiter, J.T.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Aphid
Aphids - enzymology
Base Sequence
Brevicoryne brassicae
DNA, Complementary - analysis
Evolution
Evolution, Molecular
Gene
Glucosinolate
Glycoside Hydrolases - classification
Glycoside Hydrolases - genetics
Glycoside Hydrolases - metabolism
Models, Molecular
Molecular Sequence Data
Myrosinase
Phylogeny
Protein Structure, Tertiary
Sequence Analysis, DNA
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Summary:The aphid myrosinase gene has been elucidated using Rapid Amplification of cDNA Ends—PCR. Sequencing has shown that aphid myrosinase has significant sequence similarity (35%) to plant myrosinases and other members of glycosyl hydrolase family 1 (GHF1). The residues acting as proton donor and nucleophile, in the hydrolysis of glucosinolates by aphid myrosinase, are identified as Glu 167 and Glu 374 respectively. The equivalent residues in plant myrosinase are Gln 187 and Glu 409 and for the cyanogenic β-glucosidase Glu 183 and Glu 397. Thus it would appear that the absence of a proton donor is not necessary for the hydrolysis of glucosinolates as was thought to be the case for the plant myrosinases. Aphid myrosinase appears to be more similar to animal β- O-glucosidases than to plant myrosinases, as assessed by sequence similarity and phylogenetic techniques. These results strongly suggest that myrosinase activity has twice arisen from β- O-glucosidases in plants and animals. Comparison of aphid myrosinase with plant myrosinase has highlighted Lys 173 and Arg 312 as possibly playing a crucial role in the hydrolysis of glucosinolates by aphid myrosinase.
ISSN:0965-1748
1879-0240
DOI:10.1016/S0965-1748(01)00088-1