Arabidopsis Putative Selenium-Binding Protein1 Expression Is Tightly Linked to Cellular Sulfur Demand and Can Reduce Sensitivity to Stresses Requiring Glutathione for Tolerance  

Abstract

Selenium-Binding Protein1 (SBP1) gene expression was studied in Arabidopsis (Arabidopsis thaliana) seedlings challenged with several stresses, including cadmium (Cd), selenium {selenate [Se(VI)] and selenite [Se(IV)]}, copper (Cu), zinc (Zn), and hydrogen peroxide (H 2 O 2 ) using transgenic lines expressing the luciferase (LUC) reporter gene under the control of the SBP1 promoter. In roots and shoots of SBP1::LUC lines, LUC activity increased in response to Cd, Se(VI), Cu, and H 2 O 2 but not in response to Se(IV) or Zn. The pattern of expression of SBP1 was similar to that of PRH43, which encodes the 5#-Adenylylphosphosulfate Reductase2, a marker for the induction of the sulfur assimilation pathway, suggesting that an enhanced sulfur demand triggers SBP1 up-regulation. Correlated to these results, SBP1 promoter showed enhanced activity in response to sulfur starvation. The sulfur starvation induction of SBP1 was abolished by feeding the plants with glutathione (GSH) and was enhanced when seedlings were treated simultaneously with buthionine sulfoxide, which inhibits GSH synthesis, indicating that GSH level participates in the regulation of SBP1 expression. Changes in total GSH level were observed in seedlings challenged with Cd, Se(VI), and H 2 O 2 . Accordingly, cad2-1 seedlings, affected in GSH synthesis, were more sensitive than wild-type plants to these three stresses. Moreover, wild-type and cad2-1 seedlings overexpressing SBP1 showed a significant enhanced tolerance to Se(VI) and H 2 O 2 in addition to the previously described resistance to Cd, highlighting that SBP1 expression decreases sensitivity to stress requiring GSH for tolerance. These results are discussed with regard to the potential regulation and function of SBP1 in plants.

Biochemical and Biophysical Characterization of the Selenium-binding and Reducing Site in Arabidopsis thaliana Homologue to Mammals Selenium-binding Protein 1

“…These results suggest that SBP1 may share similar functions with GSH in response to stress. In line with these results, stresses inducing SBP1 expression were also inducers of PRH43, which encodes 5Ј-adenylylphosphosulfate reductase 2, a key enzyme of the sulfur assimilation pathway and GSH biosynthesis (38). As an example, AtSBP1 and AtPRH43 are induced by cadmium, SeO 4 2Ϫ , H 2 O 2 and sulfur starvation.…”

“…Therefore, AtSBP1 may have chelating properties in vivo toward cadmium and may represent a new detoxification mechanism that plants use to face heavy metal toxicity, possibly throught direct binding to the metal (35). In addition to cadmium, AtSBP1 over-expressing A. thaliana plants showed increased tolerance to stress such as selenium and H 2 O 2 that also require GSH for detoxification (38). Overexpression of OsSBP1 in rice enhanced tolerance to various pathogens (17) and the importance of GSH in plant defense to biotic stress has been recently reviewed (39).…”

A Role for Barley Calcium-Dependent Protein Kinase CPK2a in the Response to Drought

“…Using LC-MS/MS, we identified several putative HvCPK2a-interacting partners including a membrane-localized H + -ATPase, which has been shown to be regulated by CPKs (Schaller and Sussman, 1988; Xing et al, 1996; Camoni et al, 1998a,b; Lino et al, 1998; De Nisi et al, 1999; Kinoshita and Shimazaki, 1999; Rutschmann et al, 2002), a glutathione S-transferase (GST), which is crucial in the response to various stress conditions (Bartlling et al, 1993; Cummins et al, 2011; Kumar et al, 2013), and a selenium binding protein (AtSBP) involved in tolerance to cadmium and selenium (Dutilleul et al, 2008; Hugouvieux et al, 2009; Schild et al, 2014). Another protein identified, a sucrose synthase (SUS), was found to be involved in long-term adaptation to drought stress conditions (Déjardin et al, 1999; Baud et al, 2004).…”

Stuck between a ROS and a hard place: Analysis of the ubiquitin proteasome pathway in selenocysteine treated Brassica napus reveals different toxicities during selenium assimilation

“…It is well established that inorganic selenium, such as selenate and selenite, deplete glutathione and cause oxidative stress (Hugouvieux et al, 2009;Łabanowska et al, 2012). Recently, Brassica napus (canola) plants treated with selenite rapidly accumulated mitochondrial superoxide; in response to selenite, roots reconfigured primarily metabolism -including antioxidant metabolism -to counter the effects of oxidative stress (Dimkovikj and Van Hoewyk, 2014).…”