Hyperacidification of vacuoles by the combined action of two different P-ATPases in the tonoplast determines flower color

• Published in: Cell reports (Cambridge) Vol. 6; no. 1; pp. 32 - 43
• Main Authors: Faraco, Marianna, Spelt, Cornelis, Bliek, Mattijs, Verweij, Walter, Hoshino, Atsushi, Espen, Luca, Prinsi, Bhakti, Jaarsma, Rinse, Tarhan, Eray, de Boer, Albertus H, Di Sansebastiano, Gian-Pietro, Koes, Ronald, Quattrocchio, Francesca M
• Format: Journal Article
• Language: English
• Published: United States Elsevier 01-01-2014
• Subjects: Amino Acid Sequence; Flowers - metabolism; Hydrogen-Ion Concentration; Molecular Sequence Data; Mutation; Petunia - enzymology; Petunia - metabolism; Phylogeny; Pigmentation; Proton-Translocating ATPases - genetics; Proton-Translocating ATPases - metabolism; Protons; Vacuoles - enzymology; Vacuoles - metabolism
• DOI: 10.1016/j.celrep.2013.12.009
• EISSN: 2211-1247

The acidification of endomembrane compartments is essential for enzyme activities, sorting, trafficking, and trans-membrane transport of various compounds. Vacuoles are mildly acidic in most plant cells because of the action of V-ATPase and/or pyrophosphatase proton pumps but are hyperacidified in specific cells by mechanisms that remained unclear. Here, we show that the blue petal color of petunia ph mutants is due to a failure to hyperacidify vacuoles. We report that PH1 encodes a P3B-ATPase, hitherto known as Mg2(+) transporters in bacteria only, that resides in the vacuolar membrane (tonoplast). In vivo nuclear magnetic resonance and genetic data show that PH1 is required and, together with the tonoplast H(+) P3A-ATPase PH5, sufficient to hyperacidify vacuoles. PH1 has no H(+) transport activity on its own but can physically interact with PH5 and boost PH5 H(+) transport activity. Hence, the hyperacidification of vacuoles in petals, and possibly other tissues, relies on a heteromeric P-ATPase pump.