Promoter analysis and functional implications of the selenium binding protein (SBP) gene family in ce:italic>Arabidopsis thaliana/ce:italic>

摘要

Selenium Βinding Protein (SBP, originally termed SBP56) was identified in mouse liver as a cytosolic protein that could bind radioactive selenium. SBPs are highly conserved proteins present in a wide array of species across all kingdoms and are likely to be involved in selenium metabolism. In Arabidopsis, the selenium binding protein (SBP) gene family comprises three genes (AtSBP1,AtSBP2andAtSBP3).AtSBP1andAtSBP2are clustered in a head-to-tail arrangement on chromosome IV, whileAtSBP3is located on chromosome III. In this work, we studied the promoter activity of the ArabidopsisSBPgenes, determined their tissue specificity and showed that they are differentially regulated by sodium selenite and sodium selenate. All threeSBPgenes are upregulated in response to externally applied selenium compounds and the antioxidant NAC selectively downregulatesSBP2. Although the effect onSBP2levels was the most prominent, in all cases, the concurrent exposure of plants to selenite and the antioxidant supressed the expression of theSBPgenes. We provide evidence that (at least)SBP1expression is tightly linked to detoxification processes related to oxidative stress, since it is downregulated in the presence of NAC in selenium-treated plants. Furthermore, our results suggest that SBP genes may participate in the mechanisms that sense redox imbalance.