StCDPK2 expression and activity reveal a highly responsive potato calcium-dependent protein kinase involved in light signalling

Abstract

Calcium-dependent protein kinases (CDPKs) are essential calcium sensors. In this work, we have studied StCDPK2 isoform from potato both at gene and protein level. StCdpk2 genomic sequence contains eight exons and seven introns, as was observed for StCdpk1. There is one copy of the gene per genome located in chromosome 7. StCDPK2 encodes an active CDPK of 515 aminoacids, with an apparent MW of 57 kDa, which presents myristoylation and palmitoylation consensus in its N-terminus. StCDPK2 is highly expressed in leaves and green sprouts; enhanced expression was detected under light treatment, which corresponds well with light responsive cis-acting elements found in its promoter sequence. Antibodies against the recombinant StCDPK2::6xHis protein detected this isoform in soluble and particulate fractions from leaves. StCDPK2 autophosphorylation and kinase activity are both calcium dependent reaching half maximal activation at 0.6 μM calcium. The active kinase is autophosphorylated on serine and tyrosine residues and its activity is negatively modulated by phosphatidic acid (PA). Our results reveal StCDPK2 as a signalling element involved in plant growth and development and show that its activity is tightly regulated.

Genome-wide analysis and expression profiling of calcium-dependent protein kinases in potato (Solanum tuberosum)

“…StCDPK1 was expressed in tuberizing stolons and sprouting tubers (Raíces et al 2001;Gargantini et al 2009), whereas expression of StCDPK3 was abundant in stolons, roots and leaves (Grandellis et al 2012). Transcript of another CDPK, StCDPK2, was present in all plant tissues studied and during different developmental processes -sprouting and tuberization (Giammaria et al 2011); its level was the highest in actively growing young leaves. In our experimental system, three CDPKs described before were expressed in all organs analysed, although expression of StCPK1 was very low.…”

“…StCDPK1 also plays a role in gibberellic acid (GA) signaling and influences tuberization (Gargantini et al 2009) while StCDPK2 is associated with plant growth and development (Giammaria et al 2011). An application of abscisic acid (ABA) or GA had no significant effect on the activity and expression of StCDPK2 (Giammaria et al 2011), while treatment with jasmonic acid decreased StCDPK2 expression at both these levels (Ulloa et al 2002). The expression profile of StCDPK3 under different conditions has indicated that ABA functions as a positive and GA as a negative regulator of its expression.…”

Genome-wide analysis of calcium-dependent protein kinases and their expression patterns in response to herbivore and wounding stresses in soybean

“…Studies from various organisms indicate CDPKs may respond to diverse stimuli, including light (Giammaria et al 2011), mechanical wounding (Szczegielniak et al 2005;Yang et al 2012), herbivore attacks (Romeis and Herde 2014), and pathogen elicitors (Asano et al 2012;Kobayashi et al 2012). In Arabidopsis, the cpk3 and cpk13 mutants had lower transcript levels of the plant defense gene (PDF1.2) compared to wild-type plants suffering from the Spodoptera littoralis; CPK3 was also suggested to be involved in the negative feedback regulation of the cytosolic Ca 2+ levels after herbivore attack and wounding damage (Kanchiswamy et al 2010).…”

Two calcium dependent protein kinases are differently regulated by light and have different activity patterns during seedling growth in Pharbitis nil

“…The transcript level decreased in lightgrown hypocotyls and roots, whereas in cotyledons light had an up-regulatory effect (Ullanat and Javabaskaran 2002). The higher protein accumulation and gene expression of StCDPK2 was in plants and sprouts of potato exposed to light when compared to dark-treated ones (Giammaria et al 2011). Light different regulation was also noted for other classes of enzymes such as the small family of plant calcium-independent Ser/Thr protein kinase PEPC-k (phosphoenolpyruvate carboxylase kinase) encoded by PPCK genes.…”

“…Expression of some CDPKs is induced by salt (Botella et al 1996) and osmotic stress (Pestenacz and Erdei 1996), wounding (Tsai et al 2007), fungal elicitors or pathogens (Romeis et al 2001;Szczegielniak et al 2005), changes in dark/ light conditions (Jaworski et al 2010;Giammaria et al 2011), and phytohormones (Zhang et al 2005;Khan et al 2005). In addition CDPKs are involved in a wide variety of developmental processes.…”