Liu_2001_Gene_268_207

The modified-ortho pathway genes responsible for the degradation of chlorocatechols produced from 3- and 4-chlorobenzoate in Burkholderia sp. NK8 were cloned and analyzed. The five genes predicted to encode a LysR-type transcriptional regulator, chlorocatechol 1,2-dioxygenase, chloromuconate cycloisomerase, dienelactone hydrolase, and maleylacetate reductase were designated tfdT, tfdC, tfdD, tfdE, and tfdF, respectively since they show the highest similarity to the corresponding genes of the chlorocatechol degradation gene cluster (tfdT-CDEF) of 2,4-dichlorophenoxyacetic acid degrading plasmid pJP4 from Ralstonia eutropha JMP134 (79-88% amino acid identity). TfdC of NK8 showed the highest activity against 3,5-dichlorocatechol in all kinds of chlorocatechols tested, which is a characteristic of TfdC of pJP4. By reporter gene (lacZ) analysis, tfdT of NK8 was shown to activate the transcription from the tfdC promoter. Unlike the regulators of other chlorocatechol degradation genes so far reported, 2-chlorobenzoate, 3-chlorobenzoate, 3-chlorocatechol and 4-chlorocatechol, were shown to act as effectors of TfdT.