Characterization of the genes encoding a receptor-like histidine kinase and a cognate response regulator from a biphenyl/polychlorobiphenyl-degrading bacterium, Rhodococcus sp. strain M5

We report the cloning, sequence, and expression of the bpdS and bpdT genes from Rhodococcus sp. strain M5, which are believed to encode the first two-component signal transduction system in the genus Rhodococcus, which potentially regulates biphenyl/polychlorobiphenyl metabolism in M5. BpdT has a typical responses regulator sequence (209 amino acids; 23 kDa), whereas BpdS, the predicted histidine kinase component, is an unusually large transmembrane protein (1,576 amino acids; 170 kDa) that contains ATP-binding and leucine-rich repeat motifs and some conserved residues of protein kinases. Expression of bpdST, like that of the bpdC1C2BADE degradative operon, is inducible by biphenyl.