Characterization Of A Salt-tolerant Correlative Protein Kinase, TaGSK1 From Triticum Asetivum L.

Our previous data suggrested that: the gene TaGSKl cloned from the wheat salt tolerance mutant RH8706-49 was Salt-tolerant Correlative gene. The results of transfering TaGSKl gene to Arabidopsis thaliane demonstrated that TaGSKl could promote the tolerance of plant cells to ostomic stress. Analysed by software, TaGSKl contains a calmodulin (CaM)-binding site.In this paper, the protein level assays are employed to study the TaGSKl.The full length cDNA of TaGSKl was cloned into pGEX-KG. Recombinant plasmid pGEX-KG/TaGSKl were transformed into E. coli Xa90 for expression. The expressed products were purified by affinity Chromatography on GST fusion protein purification beads .The purity of the recombinant protein was above 90% and it's Mr is about 66kD.On this basis, the characteristics of protein kinases were analyzed. We employed the natural electrophoresis to study if the TaGSKl could bind CaM and employed the western bloting to confirm. Our results demonstrated that TaGSKl could bind CaM in a Ca2+-dependent manner. TaGSKl contains the ser/thr protein kinase catalytic domain at the position from 166-178 amino acid and a ATP-binding site from 51-75 amino acid. This kinase phosphorylated itself and substrate Histone III-S in the reaction mixture, the activities of protein kinases is not regulated by Ca2+ and CaM.The reversible phosphorylation of Protein kinase plays important roles in many signal identifying and transfer in cell. The protein kinases mainly catalyse phosphorylation of proteins. The results demonstrated that TaGSKl represents a new class of CaM~binding ser/thr kinase that could promote the tolerance of plant cells to ostomic stress.