Characterization, Functional Reconstitution and Activation by Fusicoccin of a Ca^<2+>-ATPase from Corydalis sempervirens Pers. Cell Suspension Cultures

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概要

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• Cell suspension cultures of Corydalis sempervirens have proven ideal for the study of fusicoccin action [Schulz et al. (1990) Planta 183: 83] and express the fusipoccin-binding protein as well as a plasma membrane H^+-ATPase which is activated by the fungal toxin. Microsomal vesicles prepared from these cells accumulate Ca^<2+> in the presence of Mg-ATP. The protonophore carbonylcyanide m-chlorophenylhydrazone did not inhibit the Mg-ATP dependent Ca^<2+>-transport into the vesicles. This process is thus due to the activity of at least one primary active, ATP-driven, Ca^<2+>-pump. The enzyme was characterized in detail. It has a pH optimum of 7.2, an apparent K_m of 0.3 mM (ATP), 12pm (Ca^<2+>), accepts ATP>ITP≈GTP>CTP≈UTP, and is strongly (K_i, app 0.75μM) inhibited by eryihrosine B but less so (K_i, app 95 μM) by orthovanadate. These characteristics are typical for the plasma membrane Ca^<2+>-ATPase characterized from differentiated tissues [Graf and Weiler (1990) Physiol. Plant. 75: 634]. Fusicoccin activates the eryihrosine-sensitive Ca^<2+>-pump by lowering its K_m for ATP, when added to living cells prior to tissue homogenization. Thus, fusicoccin appears to activate at least two ion-translocating ATPases in one and the same tissue, suggesting that the toxin's mechanism of action is complex and not restricted to activation of the H^+-ATPase. FC has no effect when administered to microsomes. The microsomal enzyme was solubilized and reconstituted into asolectin- liposomes in functional form. The reconstituted, eryihrosine sensitive Ca^<2+>_ATPase was insensitive to fusicoccin. Thus, components essential for toxin action are either lost or inactivated during subcellular fractionation. It is likely that FC action requires soluble components.

• 日本植物生理学会の論文

著者

• Siebers Bettina

  Lehrstuhl Fur Pflanzenphysiologie Ruhr-universitat

• Weiler Elmar

  Lehrstuhl Fur Pflanzenphysiologie Ruhr-universitat

• LiB Harald

  Lehrstuhl fur Pflanzenphysiologie, Ruhr-Universitat

• Lib Harald

  Lehrstuhl Fur Pflanzenphysiologie Ruhr-universitat

関連論文

• Expression of a WIPK-Activated Transcription Factor Results in Increase of Endogenous Salicylic Acid and Pathogen Resistance in Tobacco Plants
• Characterization, Functional Reconstitution and Activation by Fusicoccin of a Ca^-ATPase from Corydalis sempervirens Pers. Cell Suspension Cultures

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