Abscisic acid activates a Ca2+-calmodulin-stimulated protein kinase involved in antioxidant defense in maize leaves.
The role of a calcium-dependent and calmodulin (CaM)-stimulated protein kinase in abscisic acid (ABA)-induced antioxidant defense was determined in leaves of maize (Zea mays). In-gel kinase assays showed that treatments with ABA or H(2)O(2) induced the activation of a 49-kDa protein kinase and a 52-kDa protein kinase significantly. Furthermore, we showed that the 52-kDa protein kinase has the characteristics of CaM-stimulating activity and is sensitive to calcium-CaM-dependent protein kinase II (CaMK II) inhibitor KN-93 or CaM antagonist W-7. Treatments with ABA or H(2)O(2) not only induced the activation of the 52-kDa protein kinase, but also enhanced the total activities of the antioxidant enzymes, including catalase, ascorbate peroxidase, glutathione reductase, and superoxide dismutase. Such enhancements were blocked by pretreatment with a CaMK inhibitor and a reactive oxygen species (ROS) inhibitor or scavenger. Pretreatment with the CaMK inhibitor also substantially arrested the ABA-induced H(2)O(2) production. Kinase activity enhancements induced by ABA were attenuated by pretreatment with an ROS inhibitor or scavenger. These results suggest that the 52-kDa CaMK is involved in ABA-induced antioxidant defense and that cross-talk between CaMK and H(2)O(2) plays a pivotal role in ABA signaling. We infer that CaMK acts both upstream and downstream of H(2)O(2), but mainly acts between ABA and H(2)O(2) in ABA-induced antioxidant-defensive signaling.
Xu
Shucheng
S
Fuyang Teachers College, China. xscjack@tom.com
D000040:Abscisic Acid / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D057075:Enzyme Assays; D005980:Glutathione Reductase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D008970:Molecular Weight; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology; D010544:Peroxidases / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D003313:Zea mays / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D000096926:Benzenesulfonamides
D000040:Abscisic Acid; D000975:Antioxidants; D060387:Ascorbate Peroxidases; D001596:Benzylamines; D002118:Calcium; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002147:Calmodulin; D002374:Catalase; D005980:Glutathione Reductase; D006861:Hydrogen Peroxide; D016877:Oxidants; D010544:Peroxidases; D010937:Plant Growth Regulators; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D013482:Superoxide Dismutase; C072105:KN 93; D000096926:Benzenesulfonamides; C017967:W 7