TY - CONF

T1 - Specialized roles for the two UDP-glucosyltransferases UGT85K2 and UGT85K3 in hydroxynitrile glucoside metabolism in Lotus japonicus

AU - Baden, Camilla Knudsen

AU - Bjarnholt, Nanna

AU - Jensen, Kenneth

AU - Robsen, Fran

AU - Olsen, Carl Erik

AU - Motawia, Mohammed Saddik

AU - Møller, Birger Lindberg

AU - Takos, Adam Matthew

AU - Rook, Fred

N1 - Poster presented at the Gordon Research Conference in Metabolic Engineering, Waterville valley, New Hampshire, USA

PY - 2013

Y1 - 2013

N2 - Cyanogenic glucosides are amino-acid derived plant chemical defense compounds against generalist herbivores. They are α-hydroxynitrile glucosides that are activated by specific β-glucosidases upon tissue disruption. The unstable α-hydroxynitrile will dissociate with the release of hydrogen cyanide. The legume model Lotus japonicus contains the cyanogenic glucosides linamarin and lotaustralin, and the non-cyanogenic γ- and β-hydroxynitrile glucosides rhodiocyanoside A and D, which are also thought to function as defense compounds. Glucosylation is a key-step in the biosynthesis of hydroxynitrile glucosides as it stabilizes and detoxifies these compounds, and allows for their storage. Both the UDP-glucosyltransferases UGT85K2 and UGT85K3 are able to catalyze the synthesis of linamarin and lotaustralin, but only UGT85K2 showed significant glucosylation activity for the synthesis of rhodiocyanosides in vitro. Mutants in the UGT85K2 gene, obtained by TILLING, almost lacked rhodiocyanosides and showed severe growth defects. This suggested the toxicity of the rhodiocyanoside aglycones and supports their proposed defense role. The observed specificity of these UGTs further highlights the metabolic flexibility of the hydroxynitrile glucoside based defense pathway in Lotus japonicus.

AB - Cyanogenic glucosides are amino-acid derived plant chemical defense compounds against generalist herbivores. They are α-hydroxynitrile glucosides that are activated by specific β-glucosidases upon tissue disruption. The unstable α-hydroxynitrile will dissociate with the release of hydrogen cyanide. The legume model Lotus japonicus contains the cyanogenic glucosides linamarin and lotaustralin, and the non-cyanogenic γ- and β-hydroxynitrile glucosides rhodiocyanoside A and D, which are also thought to function as defense compounds. Glucosylation is a key-step in the biosynthesis of hydroxynitrile glucosides as it stabilizes and detoxifies these compounds, and allows for their storage. Both the UDP-glucosyltransferases UGT85K2 and UGT85K3 are able to catalyze the synthesis of linamarin and lotaustralin, but only UGT85K2 showed significant glucosylation activity for the synthesis of rhodiocyanosides in vitro. Mutants in the UGT85K2 gene, obtained by TILLING, almost lacked rhodiocyanosides and showed severe growth defects. This suggested the toxicity of the rhodiocyanoside aglycones and supports their proposed defense role. The observed specificity of these UGTs further highlights the metabolic flexibility of the hydroxynitrile glucoside based defense pathway in Lotus japonicus.

KW - Faculty of Science

KW - plant biochemistry

KW - Molecular Biology

M3 - Poster

ER -