title: TRANSPARENT TESTA 13 is a tonoplast P3A -ATPase required for vacuolar deposition of proanthocyanidins in Arabidopsis thaliana seeds.
abstract: Intracellular pH homeostasis is essential for all living cells. In plants, pH is usually maintained by three structurally distinct and differentially localized types of proton pump: P-type H(+) -ATPases in the plasma membrane, and multimeric vacuolar-type H(+) -ATPases (V-ATPases) and vacuolar H(+) -pyrophosphatases (H(+) -PPases) in endomembranes. Here, we show that reduced accumulation of proanthocyanidins (PAs) and hence the diminished brown seed coloration found in the Arabidopsis thaliana mutant transparent testa 13 (tt13) is caused by disruption of the gene encoding the P3A -ATPase AHA10. Identification of the gene encoded by the tt13 locus completes the molecular characterization of the classical set of transparent testa mutants. Cells of the tt13 seed coat endothelium do not contain PA-filled central vacuoles as observed in the wild-type. tt13 phenocopies tt12, a mutant that is defective in vacuolar import of the PA precursor epicatechin. Our data show that vacuolar loading with PA precursors depends on TT13. Consistent with the tt13 phenotype, but in contrast to other isoforms of P-type H(+) -ATPases, TT13 localizes to the tonoplast. PA accumulation in tt13 is partially restored by expression of the tonoplast localized H(+) -PPase VHP1. Our findings indicate that the P3A -ATPase TT13 functions as a proton pump in the tonoplast of seed coat endothelium cells, and generates the driving force for TT12-mediated transport of PA precursors to the vacuole.
authors.affiliation: Genome Research, Faculty of Biology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Appelhagen
authors.affiliation: Genome Research, Faculty of Biology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany.
authors.forename: Niclas
authors.initials: N
authors.lastname: Nordholt
authors.affiliation: Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, Universitätsstraße 25, 33501, Bielefeld, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Seidel
authors.affiliation: Department for Molecular Cell Biology, VU University, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands.|Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
authors.forename: Kees
authors.initials: K
authors.lastname: Spelt
authors.affiliation: Department for Molecular Cell Biology, VU University, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands.|Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
authors.forename: Ronald
authors.initials: R
authors.lastname: Koes
authors.affiliation: Department for Molecular Cell Biology, VU University, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands.|Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
authors.forename: Francesca
authors.initials: F
authors.lastname: Quattrochio
authors.affiliation: Genome Research, Faculty of Biology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Sagasser
authors.affiliation: Genome Research, Faculty of Biology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Weisshaar
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D009154:Mutation; D032306:Petunia / Q000235:genetics; D030821:Plants, Genetically Modified; D044945:Proanthocyanidins / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D044945:Proanthocyanidins; C000607354:TT13 protein, Arabidopsis; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases
keywords: AHA10; Arabidopsis thaliana; P-ATPase; Petunia hybrida; flavonoids; proton pump; tonoplast; vacuole