title: Peptidyl-prolyl cis-trans isomerase ROF2 modulates intracellular pH homeostasis in Arabidopsis.
abstract: Intracellular pH must be kept close to neutrality to be compatible with cellular functions, but the mechanisms of pH homeostasis and the responses to intracellular acidification are mostly unknown. In the plant Arabidopsis thaliana, we found that intracellular acid stress generated by weak organic acids at normal external pH induces expression of several chaperone genes, including ROF2, which encodes a peptidyl-prolyl cis-trans isomerase of the FK506-binding protein class. Loss of function of ROF2, and especially double mutation of ROF2 and the closely related gene ROF1, results in acid sensitivity. Over-expression of ROF2 confers tolerance to intracellular acidification by increasing proton extrusion from cells. The activation of the plasma membrane proton pump (H(+) -ATPase) is indirect: over-expression of ROF2 activates K(+)  uptake, causing depolarization of the plasma membrane, which activates the electrogenic H(+)  pump. The depolarization of ROF2 over-expressing plants explains their tolerance to toxic cations such as lithium, norspermidine and hygromycin B, whose uptake is driven by the membrane potential. As ROF2 induction and intracellular acidification are common consequences of many stresses, this mechanism of pH homeostasis may be of general importance for stress tolerance.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Camino de Vera, Valencia, Spain.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Bissoli
authors.forename: Regina
authors.initials: R
authors.lastname: Niñoles
authors.forename: Sandra
authors.initials: S
authors.lastname: Fresquet
authors.forename: Samuela
authors.initials: S
authors.lastname: Palombieri
authors.forename: Eduardo
authors.initials: E
authors.lastname: Bueso
authors.forename: Lourdes
authors.initials: L
authors.lastname: Rubio
authors.forename: María J
authors.initials: MJ
authors.lastname: García-Sánchez
authors.forename: José A
authors.initials: JA
authors.lastname: Fernández
authors.forename: José M
authors.initials: JM
authors.lastname: Mulet
authors.forename: Ramón
authors.initials: R
authors.lastname: Serrano
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000737:chemistry; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D019696:Peptidylprolyl Isomerase / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011522:Protons; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012413:Rubidium / Q000378:metabolism; D059467:Transcriptome
chemical_list: D029681:Arabidopsis Proteins; D006360:Heat-Shock Proteins; D011522:Protons; D006180:Proton-Translocating ATPases; D019696:Peptidylprolyl Isomerase; C574787:ROF2 protein, Arabidopsis; D012413:Rubidium; D011188:Potassium