Modification and Translocation of Rac/Rop Guanosine 5'-Triphosphate-Binding Proteins of Scoparia dulcis in Response to Stimulation with Methyl Jasmonate

Abstract

Translocation of two Rac/Rop guanosine 5 -triphosphate-binding proteins from Scoparia dulcis, Sdrac-1 and Sdrac-2, was examined employing transformed belladonna which overproduces these proteins as glutathione-S-transferase-tagged forms. The transferase activities of the fused proteins in microsomal fraction of belladonna markedly increased by the incubation with methyl jasmonate either in Sdrac-1 or Sdrac-2 transformant, while low and constant activities were observed in the untreated control. Recombinant Sdrac-2 protein was found to bind to prenyl chain in the presence of cell extracts prepared from methyl jasmonate-treated S. dulcis, however, Sdrac-1 was palmitoylated by the addition of the cell extracts. These results suggest that both Sdrac-1 and Sdrac-2 translocate to plant membranes by the stimulation with methyl jasmonate, however, targeting of these proteins is triggered by the independent modification mechanisms, palmitoylation for Sdrac-1 and prenylation for Sdrac-2.

Transcriptional activation of sesquiterpene biosynthetic enzyme δ-guaiene synthase gene in cell cultures of Aquilaria microcarpa overexpressing cam1 and rac2 encoding calmodulin and Rac GTPase

“…It has been also shown that calmodulin, a Ca 2+ -binding protein, functions as a key mediator in the signal transduction mechanisms of MJ. In addition, we have recently demonstrated (Saitoh et al, 2007;Shite et al, 2009;Mitamura et al, 2011;Kenmotsu et al, 2013) that Rac GTPase, a plant-specific monomeric GTP-binding protein (Zeng and Yang, 2000;Gu et al, 2004;Berken, 2006), would play important roles to evoke Ca 2+ -influx in MJ-signaling processes of higher plant cells ( Fig. 1).…”

Induction and Activation of Plant Secondary Metabolism by External Stimuli

“…We also attempted to elucidate the possible post-translational modifications of these monomeric GTPases with hydrophobic groups which evoke the targeting of the proteins to plant plasma membrane (Mitamura et al, 2011). In vitro modifications of Sdrac-1 and Sdrac-2 were studied using the His-tagged recombinant proteins, and the purified Sdrac proteins were incubated with [ 14 C]-isopentenyl diphosphate, geranyl diphosphate and recombinant farnesyl diphosphate synthase protein, the [ 14 C]-farnesyl diphosphategenerating system, in the presence or absence of MJ-treated cell extracts of S. dulcis.…”