Calcium/Calmodulin-dependent Protein Kinase(s) in Plants

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Plants respond to various signals such as hormones, light and gravity. How plants perceive and transduce these chemical and physical signals is not clearly understood. Accumulating evidence indicates that calcium acts as a messenger in signal transduction in plants. Many of the signal-induced responses are mediated by calcium. Increased calcium can affect diverse physiological processes through the action of calmodulin, a ubiquitous calcium- binding protein. Much of this diversity in response in plants is believed to be achieved by the modulation of the activity of the calcium and/or calcium-calmodulin-dependent protein kinases. Although calcium/calmodulin-dependent protein phosphorylation is implicated in regulating a number of cellular processes in plants, nothing is known about the calcium/calmodulin-dependent protein kinase(s) and its substrates. Dr. Poovaiah has isolated several cDNA clones by immunoscreening the expression libraries with the antibody produced to the sequence corresponding to alpha subunit of animal calcium/calmodulin-dependent protein kinase II. The principal investigator proposes to perform biochemical analyses of the encoded protein to verify its protein kinase activity, determine its mode of regulation by calcium and calmodulin, and analyze its substrate specificity. Furthermore, Dr. Poovaiah intends to use auxin resistant mutants of Arabidopsis and light- responsive corn mutant to study the role of calcium/calmodulin- dependent protein kinase in auxin and light signal transduction, respectively. The information derived from these studies would be of immense value in understanding the role of calcium/calmodulin- dependent protein kinase(s) in signal transduction in plants.//