Casein kinase activity in etiolated Cucumis sativus cotyledons

Abstract

Two calcium- and light-dependent protein kinases have been reported in etiolated Cucumis sativus cotyledons (Vidal et al. 2007). In the present work, we studied casein kinase (CK) activity in etiolated cucumber cotyledons of in-gel and in vitro kinase assays, using specific CK inhibitors, and ATP and GTP as phosphate donors. Two proteins with CK activity were detected in both casein gels and autophosphorylation assays. One of them, with a molecular mass of approximately 36 kDa, showed biochemical CK1 characteristics: it was inhibited by specific CK1 inhibitors and only used ATP as phosphate donor. The second, with a molecular mass of approximately 38 kDa, had CK2 characteristics; it used both ATP and GTP as phosphate donors, was inhibited by all specific CK2 inhibitors, and was recognized by a polyclonal antibody directed against the alpha catalytic subunit of a CK2 from tobacco. The kinase activity of the CK2 detected in etiolated cucumber cotyledons showed circadian rhythmicity in both in vitro and in-gel casein phosphorylation and in autophosphorylation assays. Thus, our results suggest that the CK2 of approximately 38 kDa could be related to the circadian oscillator of C. sativus cotyledons.

TheCucumis sativuskinome: Identification, annotation, and expression patterns in response to powdery mildew infection

“…Some genome-wide analyses have been done in some sub-families of protein kinases (Wei et al, 2019) and dirigent gene family (Yadav et al, 2021) in the cucurbits species, there is no evidence of of comparative studies comprising all the protein kinase loci of Csa. Many genome-wide studies regarding protein kinase families in Csa have been done, such as that Mitogen-Activated Protein Kinase (MAPK) family (Shoresh et al, 2006), Casein Kinase (CK) family (Vidal et al, 2010), Calcium-Dependent Protein Kinase (CDPK) family (Xu et al, 2015); and in others plant species, such as, the CDPK family in maize (Kong et al, 2013), CDPK family in grape (Zhang et al, 2015), CDPK family and calcium-dependent protein kinase-related (CRK) family in tomato (Wang et al, 2016), Valine-glutamine (VQ) motif in melon (Zhang et al, 2017), CRK family in Gossypium barbadense (Li et al, 2018), CDPK family in watermelon (Wei et al, 2019), CDPK family in pineapple (Zhang et al, 2020), CDPK family in banana (Li et al, 2019), autophagy genes in Csa (Rui et al, 2020), CDPK and CRK families in Medicago truncatula (Zhao et al, 2021), CRK family in Aeluropus littoralis L. (Arab et al, 2021), CDPK family in apple (Dai et al, 2021), CDPK and closely related gene families in Solanum pennellii (Shi and Du, 2021), PYL gene family in Csa (Zhang et al, 2022). Beside PK families, others genome-wide studies have been done in Csa and other plant species, evidencing the need of this kind of study to Csa breeding: Cyclin-Dependent Kinase (CDK) inhibitor in avocado (Sabag et al, 2013), CDPK and related genes in Capsicum annuum (Cai et al, 2015), CDK in pumpkin (Herrera-Pola et al, 2016).…”