EVIDENCE THAT OPERON-TCB, OPERON-TFD, AND OPERON-CLC ENCODE MALEYLACETATE REDUCTASE, THE 4TH ENZYME OF THE MODIFIED ORTHO PATHWAY

The maleylacetate reductase from Pseudomonas sp. strain B13 functionin g in the modified ortho pathway was purified and digested with trypsin . The polypeptides separated by high-performance liquid chromatography were sequenced. Alignments with the polypeptides predicted from the t fdF and tcbF genes located on plasmids pJP4 of the 2,4-dichlorophenoxy acetate-degrading Alcaligenes eutrophus JMP134 and pP51 of the 1,2,4-t richlorobenzene-degrading Pseudomonas sp. strain P51 as well as polype ptides predicted from the tPE gene located on the chromosome of the 2, 4,5-trichlorophenoxyacetate-degrading Burkholderia cepacia AC1100 were obtained. In addition, the deduced protein sequence encoded by the nu cleotide sequence downstream of clcD on plasmid pAC27 of the 3-chlorob enzoate-degrading Pseudomonas putida AC866 was tested for homology. Si gnificant sequence similarities with the polypeptides encoded by the t fdF, tcbF, and tftE genes as well as the nucleotide sequence downstrea m of the clcD gene gave evidence that these genes might encode maleyla cetate reductases. A NAD-binding motif in a beta alpha beta-element wa s detected.