Isolation of a glucosyltransferase from Arabidopsis thaliana active in the metabolism of the persistent pollutant 3,4-dichloroaniline

The pollutant 3,4-dichloroaniline (DCA) was rapidly detoxified by glucosylation in Arabidopsis thaliana root cultures, with the N-beta-d-glucopyranosyl-DCA exported into the medium. The N-glucosyltransferase (N-GT) responsible for this activity was purified from Arabidopsis suspension cultures and the resulting 50 kDa polypeptide analysed by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) following tryptic digestion. The protein was identified as GT72B1. The GT was cloned and the purified recombinant enzyme shown to be highly active in conjugating DCA and 2,4,5-trichlorophenol, as well as several other chlorinated phenols and anilines, demonstrating both N-GT and O-GT activity. GT72B1 showed little activity towards natural products with the exception of the tyrosine catabolite 4-hydroxyphenylpyruvic acid. Both O-GT and N-GT activities were enhanced in both plants and cultures treated with herbicide safeners, demonstrating the chemical inducibility of this detoxification system in Arabidopsis.