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First published online January 11, 2006; 10.1104/pp.105.074971 Plant Physiology 140:558-579 (2006) © 2006 American Society of Plant Biologists Abscisic Acid Stimulates a Calcium-Dependent Protein Kinase in Grape Berry1,[W]China State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, 100094 Beijing, China
It has been demonstrated that calcium plays a central role in mediating abscisic acid (ABA) signaling, but many of the Ca2+-binding sensory proteins as the components of the ABA-signaling pathway remain to be elucidated. Here we identified, characterized, and purified a 58-kD ABA-stimulated calcium-dependent protein kinase from the mesocarp of grape berries (Vitis vinifera x Vitis labrusca), designated ACPK1 (for ABA-stimulated calcium-dependent protein kinase1). ABA stimulates ACPK1 in a dose-dependent manner, and the ACPK1 expression and enzyme activities alter accordantly with the endogenous ABA concentrations during fruit development. The ABA-induced ACPK1 stimulation appears to be transient with a rapid effect in 15 min but also with a slow and steady state of induction after 60 min. ABA acts on ACPK1 indirectly and dependently on in vivo state of the tissues. Two inactive ABA isomers, (–)-2-cis, 4-trans-ABA and 2-trans, 4-trans-(±)-ABA, are ineffective for inducing ACPK1 stimulation, revealing that the ABA-induced effect is stereo specific to physiological active (+)-2-cis, 4-trans-ABA. The other phytohormones such as auxin indoleacetic acid, gibberellic acid, synthetic cytokinin N-benzyl-6-aminopurine, and brassinolide are also ineffective in this ACPK1 stimulation. Based on sequencing of the two-dimensional electrophoresis-purified ACPK1, we cloned the ACPK1 gene. The ACPK1 is expressed specifically in grape berry covering a fleshy portion and seeds, and in a developmental stage-dependent manner. We further showed that ACPK1 is localized in both plasma membranes and chloroplasts/plastids and positively regulates plasma membrane H+-ATPase in vitro, suggesting that ACPK1 may be involved in the ABA-signaling pathway.
1 This research was supported by the China National Natural Science Foundation (grant nos. 30421002, 30330420, 30471193, and 30270919 to D.-P.Z.), the National Key Basic Research Program of China (grant no. 2003CB114302 to D.-P.Z.), and Research Programs of the China Ministry of Education (grant no. 03018 to D.-P.Z). 2 These authors contributed equally to the paper. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Da-Peng Zhang (zhangdp{at}sohu.net). [W] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.074971. * Corresponding author; e-mail zhangdp{at}sohu.net; fax 86–10–62731899. Received December 1, 2005; returned for revision December 1, 2005; accepted December 19, 2005. This article has been cited by other articles:
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