title: Extensive expression regulation and lack of heterologous enzymatic activity of the Class II trehalose metabolism proteins from Arabidopsis thaliana.
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-beta-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.
authors.affiliation: Department of Molecular Microbiology, VIB, Leuven, Belgium.
authors.forename: Matthew
authors.initials: M
authors.lastname: Ramon
authors.forename: Ive
authors.initials: I
authors.lastname: De Smet
authors.forename: Lies
authors.initials: L
authors.lastname: Vandesteene
authors.forename: Mirande
authors.initials: M
authors.lastname: Naudts
authors.forename: Barbara
authors.initials: B
authors.lastname: Leyman
authors.forename: Patrick
authors.initials: P
authors.lastname: Van Dijck
authors.forename: Filip
authors.initials: F
authors.lastname: Rolland
authors.forename: Tom
authors.initials: T
authors.lastname: Beeckman
authors.forename: Johan M
authors.initials: JM
authors.lastname: Thevelein