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PHENOXYACETIC ACID DEGRADATION BY THE 2,4-DICHLOROPHENOXYACETIC ACID (TFD) PATHWAY TO PLASMID PJP4: MAPPING AND CHARACTERIZATION OF THE TFD REGULATORY GENE, TFDR
Citation:
Harker, A., R. Olsen, AND R. Seidler. PHENOXYACETIC ACID DEGRADATION BY THE 2,4-DICHLOROPHENOXYACETIC ACID (TFD) PATHWAY TO PLASMID PJP4: MAPPING AND CHARACTERIZATION OF THE TFD REGULATORY GENE, TFDR. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-89/109.
Description:
Plasmid pJP4 enables Alcaligenes eutrophys JMP134 to dedegrade 3-chlorobenzoate and 2,4-dichlorophenoxyacetic acid (TFD). lasmid pR0101 is a derivative of pJP4 obtained by insertion of Tn1721 into a nonessential region of pJP4. lasmid pR0101 was transferred by conjugation to several Pseudomonas strains and to A. eutrophus AE0106, a cured isolate of JMP134. AE0106(pR0101) and some Pseudomonas transconjugants grew on TFD. ransconjugants with a chromosomally encoded phenol hydroxylase also degraded phenoxyacetic acid (PAA) in the presence of an inducer of the TFD pathway, namely, TFD or 3-chlorobenzoate. utant of one such phenol-degrading strain, Pseudomonas putida PP0300(pR0101), grew on PAA as the sole carbon source in the absence of inducer. his isolate carried a mutant plasmid, designated pR0103, derived from pR0101 through the deletion of a 3.9-kilobase DNA fragment. lasmid pR0103 constitutively expressed the TFD pathway, and this allowed the metabolism of PAA inthe absence of the inducer, TFD. omplementation of pR0103 in trans by a DNA fragment corresponding to the fragment deleted in pR0101 indicates that a negative control-regulatory gene (tfdR) is located on the BamHI E fragment derived from pRO101. This subclone, in the absence of other pRO101 DNA, constitutively expressed the tfdA gene and allowed PPO300 to grow on PAA. Preliminary evidence suggests that the monooxygenase activity encoded by this DNA fragment is feedback-inhibited by phenols.