Membrane hyperpolarization and salt sensitivity induced by deletion of PMP3, a highly conserved small protein of yeast plasma membrane

Abstract

Yeast plasma membranes contain a small 55 amino acid hydrophobic polypeptide, Pmp3p, which has high sequence similarity to a novel family of plant polypeptides that are overexpressed under high salt concentration or low temperature treatment. The PMP3 gene is not essential under normal growth conditions. However, its deletion increases the plasma membrane potential and confers sensitivity to cytotoxic cations, such as Na + and hygromycin B. Interestingly, the disruption of PMP3 exacerbates the NaCl sensitivity phenotype of a mutant strain lacking the Pmr2p/Enap Na + -ATPases and the Nha1p Na + /H + antiporter, and suppresses the potassium dependency of a strain lacking the K + transporters, Trk1p and Trk2p. All these phenotypes could be reversed by the addition of high Ca 2+ concentration to the medium. These genetic interactions indicate that the major effect of the PMP3 deletion is a hyperpolarization of the plasma membrane potential that probably promotes a nonspeci®c in¯ux of monovalent cations. Expression of plant RCI2A in yeast could substitute for the loss of Pmp3p, indicating a common role for Pmp3p and the plant homologue.

HOR7, a Multicopy Suppressor of the Ca2+-induced Growth Defect in Sphingolipid Mannosyltransferase-deficient Yeast

“…This would be consistent with the low pH sensitivity of Hor7p-overproducing cells. A similar function has previously been attributed to Pmp3p, a small 55-residue hydrophobic polypeptide found in the yeast plasma membrane with high sequence similarity to a family of plant polypeptides that are induced by high salinity (40). Whereas removal of Pmp3p causes a hyperpolarization of the plasma membrane (40), loss of Hor7p had no obvious effect on the membrane potential (this study).…”

Characterization of two plasma membrane protein 3 genes (PutPMP3) from the alkali grass, Puccinellia tenuiflora, and functional comparison of the rice homologues, OsLti6a/b from rice

“…4A). As the electric potential of the plasma membrane has been reported to be a major determinant of toxic cation tolerance, such as hygromycin B, these results suggest that both PutPMP3 genes abolish the membrane hyperpolarization resulting from PMP3 disruption (15). The high NaCl sensitivity of the pmp3 mutant was also complemented by the expression of PutPMP3 genes, and the divalent cations Ca 2+ or Mg 2+ completely reversed the salt sensitive phenotype in wild type, the pmp3 mutant, and the PutPMP3 transformants.…”

“…YR93-1 (Δpmr2Δnha1) was used as a control. YR93-1 is highly sensitive to salt when compared to wild type (YR93), because the YR93-1 strain is disrupted for both the plasma membrane Na + -ATPase (PMR2) and Na + /H + antiporter (NHA1), affecting the direct Na + efflux system (15). http://bmbreports.org…”

“…These proteins belong to the yeast plasma membrane protein 3 (PMP3) family. The yeast pmp3 mutant, which lacks the PMP3 gene, accumulates excess Na + ions within the cell and demonstrates an increased Na + sensitivity (15,16). Loss of PMP3 has been suggested to induce hyperpolarization of the membrane potential and promote a nonspecific influx of monovalent cations.…”

Incomplete Penetrance and Variable Expressivity of a Growth Defect as a Consequence of Knocking Out Two K+ Transporters in the Euascomycete Fungus Podospora anserina

“…Cells that have a hyperpolarcan be attributed to the lack of the protein PaTRK-1. Evidence that the protein encoded by Patrk-1 was inized membrane are sensitive to these drugs (McCusker et al 1987;Navarre and Goffeau 2000). Sensitivity to volved in K ϩ homeostasis came from the fact that addition of KCl, but not of NaCl, corrected the thermal sensitivhygromycin B and TMA was measured in ⌬Patrk-1 from both its normal and its strong Wavy forms and compared ity and reduced growth on ammonium-containing media of ⌬Patrk-1.…”