Abstract
Ca2+ signaling plays an essential role in a plant's perception and response to biotic and abiotic stimuli as well as in regulating many aspects of growth and development. Calcium-dependent protein kinases (CDPKs) are sensor-transducer proteins capable of decoding calcium signals in diverse phosphorylation-dependent calcium signaling networks. To understand the specific functional roles of CDPK, a high-throughput yeast two-hybrid screening has carried out to identify CDPK substrates and interacting protein. Wild type, catalytically impaired, and constitutively active kinase mutants were used as baits in a robotic-based, interaction-screening program. The use of constitutively active CDPK baits was found to improve the efficiency of recovering positive interactors relative to the wildtype kinase. Several candidate substrates have been confirmed in vitro including proteins that are supposed to be involved in osmotic stress, chloroplast protein import, transcriptional regulation, and disease resistance. These results should provide novel insights into the multifunctional calcium signaling processes of plants.
