Extensive expression regulation and lack of heterologous enzymatic activity of the Class II trehalose metabolism proteins from Arabidopsis thaliana |
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Authors: | MATTHEW RAMON IVE DE SMET LIES VANDESTEENE MIRANDE NAUDTS BARBARA LEYMAN PATRICK VAN DIJCK FILIP ROLLAND TOM BEECKMAN & JOHAN M THEVELEIN |
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Institution: | Department of Molecular Microbiology, VIB, Leuven, Belgium,;Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, K.U.Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium,;Department of Plant Systems Biology, VIB, Ghent, Belgium and;Department of Plant Systems Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium |
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Abstract: | Trehalose metabolism has profound effects on plant growth and metabolism, but the mechanisms involved are unclear. In Arabidopsis , 21 putative trehalose biosynthesis genes are classified in three subfamilies based on their similarity with yeast TPS1 (encoding a trehalose-6-phosphate synthase, TPS) or TPS2 (encoding a trehalose-6-phosphate phosphatase, TPP). Although TPS1 (Class I) and TPPA and TPPB (Class III) proteins have established TPS and TPP activity, respectively, the function of the Class II proteins (AtTPS5-AtTPS11) remains elusive. A complete set of promoter- β -glucurinidase/green fluorescent protein reporters demonstrates their remarkably differential tissue-specific expression and responsiveness to carbon availability and hormones. Heterologous expression in yeast furthermore suggests that none of the encoded enzymes displays significant TPS or TPP activity, consistent with a regulatory rather than metabolic function for this remarkable class of proteins. |
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Keywords: | Arabidopsis thaliana Class II TPS genes expression regulation metabolic activity sugar-and hormone responses trehalose metabolism |
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