In Arabidopsis thaliana, the putative selenium-binding protein gene family is made of 3 members (SBP 1 to 3). RT-PCR analyses showed that SBP1 expression was ubiquitous. SBP2 was expressed at a lower level in flowers and roots whereas SBP3 transcripts were only detected in young seedling tissues. In Cd-treated seedlings, SBP1 level of expression was rapidly increased in roots. In shoots, SBP1 transcripts accumulated later and for higher Cd doses. SBP2 and SBP3 expression showed delayed or no responsiveness to Cd. In addition, luciferase (LUC) activity recorded on Arabidopsis lines expressing the LUC gene under the control of SBP1 promoter further showed dynamic regulation of SBP1 expression during development and in response to Cd stress. Western blot analysis using polyclonal antibodies raised against SBP1 showed that SBP1 protein accumulated in Cd-exposed tissues in correlation with SBP1 transcript amount. The sbp1 null mutant displayed no visible phenotype under normal and stress conditions that was explained by the up regulation of SBP2 expression. SBP1 over-expression enhanced Cd accumulation in roots and reduced sensitivity to Cd in WT and more significantly in Cd-hypersensitive cad mutants that lack phytochelatins. Similarly in Saccharomyces cerevisiae, SBP1 expression led to increased Cd tolerance of the Cd-hypersensitive ycf1 mutant. In vitro experiments showed that SBP1 has the ability to bind Cd. These data highlight the importance of maintaining the adequate SBP protein level under healthy and stress conditions and suggest that during Cd stress, SBP1 accumulation efficiently helps to detoxify Cd potentially through direct binding.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|