title: Inhibition of SNF1-related protein kinase1 activity and regulation of metabolic pathways by trehalose-6-phosphate.
abstract: Trehalose-6-phosphate (T6P) is a proposed signaling molecule in plants, yet how it signals was not clear. Here, we provide evidence that T6P functions as an inhibitor of SNF1-related protein kinase1 (SnRK1; AKIN10/AKIN11) of the SNF1-related group of protein kinases. T6P, but not other sugars and sugar phosphates, inhibited SnRK1 in Arabidopsis (Arabidopsis thaliana) seedling extracts strongly (50%) at low concentrations (1-20 microM). Inhibition was noncompetitive with respect to ATP. In immunoprecipitation studies using antibodies to AKIN10 and AKIN11, SnRK1 catalytic activity and T6P inhibition were physically separable, with T6P inhibition of SnRK1 dependent on an intermediary factor. In subsequent analysis, T6P inhibited SnRK1 in extracts of all tissues analyzed except those of mature leaves, which did not contain the intermediary factor. To assess the impact of T6P inhibition of SnRK1 in vivo, gene expression was determined in seedlings expressing Escherichia coli otsA encoding T6P synthase to elevate T6P or otsB encoding T6P phosphatase to decrease T6P. SnRK1 target genes showed opposite regulation, consistent with the regulation of SnRK1 by T6P in vivo. Analysis of microarray data showed up-regulation by T6P of genes involved in biosynthetic reactions, such as genes for amino acid, protein, and nucleotide synthesis, the tricarboxylic acid cycle, and mitochondrial electron transport, which are normally down-regulated by SnRK1. In contrast, genes involved in photosynthesis and degradation processes, which are normally up-regulated by SnRK1, were down-regulated by T6P. These experiments provide strong evidence that T6P inhibits SnRK1 to activate biosynthetic processes in growing tissues.
authors.affiliation: Plant Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lucia F
authors.initials: LF
authors.lastname: Primavesi
authors.forename: Deveraj
authors.initials: D
authors.lastname: Jhurreea
authors.forename: P John
authors.initials: PJ
authors.lastname: Andralojc
authors.forename: Rowan A C
authors.initials: RA
authors.lastname: Mitchell
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Powers
authors.forename: Henriette
authors.initials: H
authors.lastname: Schluepmann
authors.forename: Thierry
authors.initials: T
authors.lastname: Delatte
authors.forename: Astrid
authors.initials: A
authors.lastname: Wingler
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Paul
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020134:Catalytic Domain; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005964:Glucosyltransferases / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000187:drug effects*; D020411:Oligonucleotide Array Sequence Analysis; D010936:Plant Extracts / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D012984:Software; D013403:Sugar Phosphates / Q000494:pharmacology*; D014157:Transcription Factors / Q000378:metabolism; D014199:Trehalose / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000255:Adenosine Triphosphate; D029681:Arabidopsis Proteins; D005964:Glucosyltransferases; D010936:Plant Extracts; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D013403:Sugar Phosphates; D014157:Transcription Factors; D014199:Trehalose; C082722:trehalose-6-phosphate; C023180:trehalose-6-phosphate synthase; C531469:At3g01090 protein, Arabidopsis