Role of Calcium/Calmodulin in Plant Stress Response and Signaling
Calcium is a common intracellular second messenger in all the eukaryotes, regulating plethora of cellular processes. Many effects of calcium are mediated by calmodulin superfamily of calcium-binding regulatory protein. Calmodulin is a ubiquitously found a
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Abstract
Calcium is a common intracellular second messenger in all the eukaryotes, regulating plethora of cellular processes. Many effects of calcium are mediated by calmodulin superfamily of calcium-binding regulatory protein. Calmodulin is a ubiquitously found and highly conserved calcium sensor throughout eukaryotes; it plays a critical role in calcium-mediated signaling involved in a myriad of cellular processes and responses. Calmodulin works by binding to short peptide sequences in target proteins, bringing about structural changes, which alter the activity of target proteins in response to changes in intracellular calcium level. Plants have evolved a complex network of calmodulin and calmodulinbinding target proteins that serve to play an important role in mediating stress-signaling pathways. Many of the calmodulin-binding proteins include transcription factors, ion channels, and metabolic enzymes that assist plant to effectively cope with environmental stress and pathogens. Extensive research over the past decade has been focused on understanding the function of calmodulin in biotic and abiotic stress response. Several studies employing genetic, molecular biology and biochemical techniques have yielded interesting insights into the function of calmodulin in modulating its various targets to provide stress resistance. In this chapter, we attempt to summarize the major findings about the regulatory role of CaM and its target proteins in abiotic and biotic stress response.
R. Das Department of Biology, University of Rochester, Rochester, NY 14627, USA A. Pandey G.K. Pandey (*) Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi 110021, India e-mail: [email protected] R.K. Gaur and P. Sharma (eds.), Approaches to Plant Stress and their Management, DOI 10.1007/978-81-322-1620-9_4, # Springer India 2014
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Keywords
CaM- Calcium-modulated protein CML- CaM-like protein EF-hand AtSRs/CAMTAs- (CaM-binding transcription activator) CBP- CaMbinding protein cDNA expression library HRP- Horseradish peroxidase CaMBD- CaM-binding domain
Introduction Calmodulin was first discovered by Ebashi and Kodama (1965) who demonstrated calcium requirement of calcium-binding protein troponin C in skeletal muscle. Later studies (Cheung 1971) also showed requirement of calcium by an activator for cyclic nucleotide phosphodiesterase in regulating cAMP levels. The “activator”/calcium-binding protein in both cases was found to be structurally similar and named as calmodulin (CaM) or calcium-modulated protein, present in all eukaryotes. The first CaM sequence reported in bovine showed it to be an acidic, single polypeptide containing protein, 148 amino acid long, having a molecular weight close to 16.7 kDa (Watterson et al. 1980), and an isoelectric point (pI) of 3.9–4.3. Survey of genomes of different organisms revealed a greater diversity in sequence of CaM displayed by plants unlike animals that have only few genes encoding calm
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