Molecular cloning and expression of a glycosyltransferase from Bacillus subtilis for modification of morin and related polyphenols.

ABSTRACT

OBJECTIVES: To characterize glycosyltransferases from Bacillus subtilis ATCC 6633 and investigate their substrate specificity towards plant polyphenols. RESULTS: Among the cloned and expressed six UDP-glycosyltransferases (BsGT1-6), BsGT-1 showed activity with a wide range of polyphenols morin, quercetin, alizarin, rehin, curcumin and aloe emodin. The gene of BsGT-1 has an ORF of 1206 bp encoding 402 amino acids. The recombinant enzyme was purified to homogeneity by Ni-NTA affinity chromatograph, and its biochemical characteristics were identified by HPLC-UV/MS, 1H-NMR and 13C-NMR. BsGT-1 has an MW of approx. 46 kDa as indicated by SDS-PAGE; its activity was optimal at 40 °C and pH 8.5. The Km value of BsGT-1 towards morin was 110 µM. CONCLUSIONS: BsGT-1 from B. subtilis was cloned. It had high catalytic capabilities towards polyphenols which would make it feasible for the structural modification of polyphenols.