A Rice Membrane Calcium-Dependent Protein Kinase Is Induced by Gibberellin

Abstract

A rice (Oryza sativa) seed plasma-membrane calcium-dependent serine/threonine protein kinase (CDPK) has been partially purified.Comparing results in seeds that were treated with and without the plant hormone gibberellin (CA) for 10 min showed that rice CDPK was highly induced by GA. After separating solubilized membrane proteins by sodium dodecyl sulfate-gel electrophoresis, followed by renaturation, a radiolabeled phosphoprotein band of approximately 58 k D was detected, and it was apparently produced by autophosphorylation. There are five aspects of the rice CDPK that show similarity t o mammalian protein kinase C (PKC) and t o other plant CDPKs: (a) Histone l l l S and PKC peptide-ser25 (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. (d) Addition of calmodulin has no effect on the activity of the enzyme; however, the CDPK is inhibited by the calmodulin antagonists trifluoperazine and W-7. (e) The rice CDPK reacts with a mammalian anti-PKC antibody i n immunoblotting analysis. However, there is one major difference between the rice CDPK and other CDPKs: the rice CDPK is induced by CA, whereas no mammalian PKC or other plant CDPKs are known to be induced by any h o r m o n e.

A Calcium and Free Fatty Acid-Modulated Protein Kinase as Putative Effector of the Fusicoccin 14-3-3 Receptor

“…These assays were done in the presence of high calcium. The concentration of trifluoperazine necessary to inhibit 50% of the kinase activity is higher than reported by others for CDPKs (Abo-El-Saad and Wu, 1995), which may be due to the different substrates used.…”

Calcium-Dependent Protein Kinase Isoforms inPetuniaHave Distinct Functions in Pollen Tube Growth, Including Regulating Polarity

“…In plants, high [Ca 2þ ] i is also required for the aggregation, fusion, and exocytosis of secretory vesicles at the plasma membrane and may be responsible for triggering these processes (Battey and Blackbourne, 1993;Roy et al, 1999). A true PKC homolog has not been found in plant genomes, and CDPKs have been hypothesized to fulfill at least some of the functions of PKC in plants (Nanmori et al, 1994;Abo-El-Saad and Wu, 1995). The results presented suggest that Pi CDPK1 is a good candidate for performing at least some PKC functions related to secretion in plants.…”

A chemical-genetic approach to elucidate protein kinase function in planta

“…Transcriptional activation of CDPK genes was reported after abiotic stress stimuli such as cold (Monroy and Dhindsa 1995;Saijo et al 2000;Urao et al 1994), high salinity (Botella et al 1996;Saijo et al 2000;Urao et al 1994;Yoon et al 1999), mechanical disturbances (Botella et al 1996;Yoon et al 1999), or drought (Patharkar and Cushman 2000). CDPK transcript accumulation was also induced by plant pathogen-related signals such as elicitation with non-specific fungal elicitors and in a race-specific Cf-9/Avr9 gene-for-gene interaction (Chico et al 2002;Romeis et al 2001;Yoon et al 1999), or upon treatment with phytohormones, such as gibberellin, auxin, cytokinin and abscisic acid (Aboelsaad and Wu 1995;Botella et al 1996;Davletova et al 2001;Komatsu et al 2001;Yoon et al 1999). Furthermore, biochemical characterization showed an increase in CDPK auto-phosphorylation or protein kinase activity upon wounding or exposure to cold stress (Chico et al 2002;Martin and Busconi 2001).…”