Synthesis of highly hydroxylated aromatics by evolved biphenyl dioxygenase and subsequent dihydrodiol dehydrogenase.

The evolved bphA1 (2049) gene, in which nine amino acids from the Pseudomonas pseudoalcaligenes KF707 BphA1 were changed to those from the Burkholderia xenovorans LB400 BphA1 (M247I, H255Q, V258I, G268A, D303E, -313G, S324T, V325I, and T376N), was expressed in Escherichia coli along with the bphA2A3A4 and bphB genes derived from strain KF707. This recombinant E. coli cells converted biphenyl and several heterocyclic aromatic compounds into the highly hydroxylated products such as biphenyl-2,3,2',3'-tetraol (from biphenyl), 2-(2,3-dihydroxyphenyl)benzoxazole-4,5-diol (from 2-phenylbenzoxazole), and 2-(2,5-dihydroxyphenyl)benzoxazole-4,5-diol [from 2-(2-hydroxyphenyl)benzoxazole]. The antioxidative activity of these generated compounds was markedly higher than that of the original substrate used.