Isolation, characterization and docking studies of 2,3-dihydroxybiphenyl 1,2-dioxygenase from an activated sludge metagenome.

A 2,3-dihydroxybiphenyl-1,2-dioxygenase gene (designated as bphC_meta) was identified in activated sludge metagenome by PCR. This gene shared 99% sequence identity with BphC from Burkholderia xenovorans LB400. The enzyme was purified from recombinant Escherichia coli with a subunit molecular mass of 32 ± 1 kDa. It was optimally active at pH 9.0 and 40°C, using 2,3-dihydroxybiphenyl as a substrate. Activity toward substituted catechols was: 2,3-dihydroxybiphenyl > 3-methylcatechol > catechol > 4-chlorocatechol (4-methylcatechol). The prediction made by molecular docking was consistent with the kinetic experimental data, and further explained the substrate preference of BphC_meta. The present study could pave the way for the improved understanding and application of BphCs derived from metagenomes.