The arabidopsis sulfotransferase AtSOT12 plays important roles in plant defense by modifying salicylic acid and xenobiotics

Sulfonation constitutes an important reaction in the metabolism of numerous endogenous compounds and xenobiotics in mammals. In plants, sulfonation also plays an important role in plant growth, intermolecular recognition and modulation of signaling to stress. AtSOT12 (At2g03760) is one of the AtSOTs that have been most demonstrated on both of functions and structure, though the overall research on AtSOTs is limited. In this study, the tobacco transgenic plants overexpressing the Arabidopsis AtSOT12 gene were generated. Two transgenic lines named as A7 and A9 performed stable overexpression of AtSOT12 gene and will be used for further study. Enzymatic activity assay showed that AtSOT12 catalyzes the sulfonation of salicylic acid (SA), suggesting that AtSOT12 may regulate the pathogen defense and systemic acquired response (SAR) via modifying the plant hormone SA. AtSOT12 also catalyzes the sulfonation of cycloheximide (CHX) and uncharged simple phenolic compounds such as nitrophenols, ethylphenols and cresols with high efficiencies. Testing of a number of compounds for AtSOT12 suggests that, instead of hydrophilic compounds, AtSOT12 prefers uncharged, hydrophobic substrates. The high similarities of crystal structures among AtSOT12, SULT1A1 and SULT1E1, could provide an insight of structural characteristics of AtSOT12 for further study.