title: Abscisic acid stimulates a calcium-dependent protein kinase in grape berry.
abstract: 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.
authors.affiliation: China State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, 100094 Beijing, China.
authors.forename: Xiang-Chun
authors.initials: XC
authors.lastname: Yu
authors.forename: Mei-Jun
authors.initials: MJ
authors.lastname: Li
authors.forename: Gui-Feng
authors.initials: GF
authors.lastname: Gao
authors.forename: Hai-Zhong
authors.initials: HZ
authors.lastname: Feng
authors.forename: Xue-Qing
authors.initials: XQ
authors.lastname: Geng
authors.forename: Chang-Cao
authors.initials: CC
authors.lastname: Peng
authors.forename: Sai-Yong
authors.initials: SY
authors.lastname: Zhu
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Wang
authors.forename: Yuan-Yue
authors.initials: YY
authors.lastname: Shen
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Zhang
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D015139:Blotting, Southern; D002118:Calcium / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure; D003001:Cloning, Molecular; D005638:Fruit / Q000187:drug effects / Q000201:enzymology; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation; D027843:Vitis / Q000187:drug effects / Q000201:enzymology*
chemical_list: D008565:Membrane Proteins; D010940:Plant Proteins; D000040:Abscisic Acid; D011494:Protein Kinases; D002118:Calcium