Salt Tolerance-Related Protein: a new protein involved in response to cold stress in Arabidopsis thaliana.

Salt tolerant-related protein (STRP), is a poorly characterized protein identified in a proteomic screen in Arabidopsis, resulted to be strongly increased after cold stress (Rocco et al., 2013). Protein structure and function are unknown, and just few information are available. It is involved in plant response to salt stress and knockout mutants are hypersensitive to this stress (Du et al., 2008). Recently has been highlighted that DEK3, a member of a protein family involved in chromatin remodeling, could interact with STRP (Waidmann et al., 2014). In order to to clarify the physiological function of STRP and its role in the response to cold stress we performed genetic and biochemical studies, including reverse genetic, gene expression studies, and protein function analysis. We generated Arabidopsis STRP-overexpressing plants by Agrobacterium-mediated transformation, and we obtained Strp knockout mutants by the Nottingham Arabidopsis Stock Center. Phenotypical analysis of overexpressing plants and strp knockout has been be carried out, and plant responses to cold stress (oxidative damage, membrane lipid modification, production of osmoprotectant solutes, cold-related gene expression) has been evaluated. For biochemical studies, the STRP recombinant protein has been produced in Escherichia coli. This protein has been purified and used to obtain an anti-STRP polyclonal antibody By using anti-STRP antibody, we analyzed STRP protein in different cell compartments and we investigated the effect of cold stress on protein localization. Moreover, we evaluated the possible transcriptional (Real Time PCR), post-transcriptional (protein-synthesis inhibitors) or post-translational (proteasome inhibitors) regulation of STRP in stress conditions.