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          Institute: MPI für molekulare Pflanzenphysiologie     Collection: Publikationen Pflanzenphysiologie     Display Documents

ID: 251478.0, MPI für molekulare Pflanzenphysiologie / Publikationen Pflanzenphysiologie
Trehalose 6-phosphate regulates starch synthesis via posttranslational redox activation of ADP-glucose pyrophosphorylase
Authors:Kolbe, A.; Tiessen, A.; Schluepmann, H.; Paul, M.; Ulrich, S.; Geigenberger, P.
Date of Publication (YYYY-MM-DD):2005-08-02
Title of Journal:Proceedings of the National Academy of Sciences of the United States of America
Journal Abbrev.:P Natl Acad Sci USA
Issue / Number:31
Start Page:11118
End Page:11123
Review Status:not specified
Audience:Not Specified
Abstract / Description:Trehalose is the most widespread disaccharide in nature, occurring in bacteria, fungi, insects, and plants. Its precursor, trehalose 6-phosphate (T6P), is also indispensable for the regulation of sugar utilization and growth, but the sites of action are largely unresolved. Here we use genetic and biochemical approaches to investigate whether T6P acts to regulate starch synthesis in plastids of higher plants. Feeding of trehalose to Arabidopsis leaves led to stimulation of starch synthesis within 30 min, accompanied by activation of ADP-glucose pyrophosphorylase (AGPase) via post-translational redox modification. The response resembled sucrose but not glucose feeding and depended on the expression of SNF1-related kinase. We also analyzed transgenic Arabidopsis plants with T6P levels increased by expression of T6P synthase or decreased by expression of T6P phosphatase (TPP) in the cytosol. Compared with wild type, leaves of T6P synthase-expressing plants had increased redox activation of AGPase and increased starch whereas TPP-expressing plants showed the opposite. Moreover: TPP expression prevented the increase in AGPase activation in response to sucrose or trehalose feeding. Incubation of intact isolated chloroplasts with 100 mu M T6P significantly and specifically increased reductive activation of AGPase within 15 min. Results provide evidence that T6P is synthesized in the cytosol and acts on plastidial metabolism by promoting thioredoxin-mediated redox transfer to AGPase in response to cytosolic sugar levels, thereby allowing starch synthesis to be regulated independently of light. The discovery informs about the evolution of plant metabolism and how chloroplasts of prokaryotic origin use an intermediate of the ancient trehalose pathway to report the metabolic status of the cytosol.
Free Keywords:snf1 kinase
; sugar signaling
; thioredoxin
; thioredoxin-interacting protein
; potato-tubers
; adpglucose pyrophosphorylase
; saccharomyces-cerevisiae
; arabidopsis-thaliana
; reductive activation
; chloroplast enzymes
; subunit structure
; sucrose
; trehalose-6-phosphate
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für molekulare Pflanzenphysiologie/Metabolische Netzwerke/AG Geigenberger
External Affiliations:Max Planck Inst Mol Plant Physiol, Muhlenberg 1, D-14476 Golm, Germany
Max Planck Inst Mol Plant Physiol, D-14476 Golm, Germany
Univ Utrecht, Dept Mol Plant Physiol, NL-3594 CH Utrecht, Netherlands
Rothamsted Res, Harpenden AL5 2JQ, Herts, England
Identifiers:ISI:000231102400069 [ID No:1]
ISI:000231102400069 [ID No:2]
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