ANALYSIS OF DUPLICATED GENE-SEQUENCES ASSOCIATED WITH TFDR AND TFDS IN ALCALIGENES-EUTROPHUS JMP134

Plasmid pJP4 of Alcaligenes eutrophus JMP134 encodes the degradation o f 2,4-dichlorophenoxyacetic acid. A 1.2-kb BamHI-XhoI region of the re striction fragment BamHI-E has been proposed to contain the regulatory gene tfdR (A. R. Harker, R. H. Olsen, and R. J. Seidler, J. Bacteriol . 171:314-320, 1989; B. Kaphammer, J. J. Kukor, and R. H. Olsen, J. Ba cteriol. 172:2280-2286, 1990). When sequenced and analyzed, the region is shown to contain two incomplete open reading frames (ORFs) positio ned divergently. The complete DNA sequence for one of the two ORFs was obtained by sequencing the adjacent restriction fragment BamHI-F. The DNA sequence reveals 100% identity with the regulatory gene tfdS of p JP4. An XbaI-PstI fragment, containing the complete ORF, encodes a 32, 000-Da protein which binds to the promoter regions upstream from tfdA and tfdDII. The deduced amino acid sequence of the complete ORF shows similarity with sequences of activator proteins TcbR, CatM, and CatR o f the LysR family. The complete ORF represents the regulatory gene tfd R. The deduced amino acid sequence of the incomplete ORF, situated div ergently from tfdR, indicates similarity to chloromuconate cycloisomer ases produced by genes tfdD and tcbD of plasmids pJP4 and pP51, respec tively. This ORF is identified as part of a putative isofunctional gen e, tfdDII.