Elicitor-activated phospholipase A(2) generates lysophosphatidylcholines that mobilize the vacuolar H(+) pool for pH signaling via the activation of Na(+)-dependent proton fluxes.
The elicitation of phytoalexin biosynthesis in cultured cells of California poppy involves a shift of cytoplasmic pH via the transient efflux of vacuolar protons. Intracellular effectors of vacuolar proton transport were identified by a novel in situ approach based on the selective permeabilization of the plasma membrane for molecules of < or = 10 kD. Subsequent fluorescence imaging of the vacuolar pH correctly reported experimental changes of activity of the tonoplast proton transporters. Lysophosphatidylcholine (LPC) caused a transient increase of the vacuolar pH by increasing the Na(+) sensitivity of a Na(+)-dependent proton efflux that was inhibited by amiloride. In intact cells, yeast elicitor activated phospholipase A(2), as demonstrated by the formation of LPC from fluorescent substrate analogs, and caused a transient increase of endogenous LPC, as determined by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. It is suggested that LPC generated by phospholipase A(2) at the plasma membrane transduces the elicitor-triggered signal into the activation of a tonoplast H(+)/Na(+) antiporter.
Institute of Pharmaceutical Biology, Department of Cell Physiology, Martin-Luther-University, 06120 Halle, Germany.
Katrin
K
Viehweger
Batsuch
B
Dordschbal
Werner
W
Roos
D000584:Amiloride / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D005452:Fluoresceins / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008244:Lysophosphatidylcholines / Q000096:biosynthesis* / Q000494:pharmacology; D018613:Microscopy, Confocal; D028101:Papaveraceae / Q000166:cytology / Q000201:enzymology*; D010741:Phospholipases A / Q000187:drug effects / Q000378:metabolism*; D010936:Plant Extracts / Q000096:biosynthesis; D012717:Sesquiterpenes; D015398:Signal Transduction / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000187:drug effects / Q000378:metabolism*; D013729:Terpenes; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014617:Vacuoles / Q000201:enzymology; D000094162:Phytoalexins
D005452:Fluoresceins; D008244:Lysophosphatidylcholines; D010936:Plant Extracts; D012717:Sesquiterpenes; D017923:Sodium-Hydrogen Exchangers; D013729:Terpenes; C024098:6-carboxyfluorescein; D012965:Sodium Chloride; D000584:Amiloride; D010741:Phospholipases A; D025262:Vacuolar Proton-Translocating ATPases; D000094162:Phytoalexins