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A study was conducted to determine and describe the tftCD gene to characterize the upper portion of the aromatic compound 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) pathway in Burkholderia cepacia. Plasmid-preparative columns were utilized to perform a large-scale purification of cosmids while agarose plugs with intact chromosomal DNA were determined from overnight cultures. Results showed that the genes encoding the 2,4,5-T oxygenase, tftAB, were on replicon IV.

The Burkholderia cepacia AC1100 oxygenase (TftAB) converts 2,4,5-trichlorophenoxyacetic acid to 2,4,5-trichlorophenol and many other chlorinated aromatic phenoxyacetates to their phenolic derivatives. The rate of substrate consumption by TftAB depends upon the degree of substrate chlorination, chlorines position and phenoxy group. There is a mechanistic similarity between TftAB and TfdA of Alcaligenes eutrophus. Escherichia coli and Burkholderia cepacia expresses the promoter cloned upstream of the beta-galactosidase gene and show beta-galactosidase activity.

Sequencing of the 2.7-kb Sst-XbaI DNA fragment involved in the conversion of 2,4,5-T, the carbon source of Pseudomonas cepacia, to 2,4,5-trichlorophenol, indicates the presence of two open reading frames (ORFs) in the fragment. The ORFs are homologous to the BenA and BenB and XylX and XylX proteins and other biodegradative dioxygenase complexes in their amino acid sequences. Pulse-labeling experiments enable the identification of the directions of transcription of these genes and the number and sizes of the polypeptide synthesized. The enzymes encoded by the two ORFs, TftA1 and TftA2, exhibit a relaxed substrate specificity.

The transcriptional regulation of algC, a distantly located alginate biosynthetic gene in the Pseudomonas aeruginosa chromosome, was studied. Transcriptional activation of algC increases with the osmolarity of the medium and is dependent on the response regulator, AlgR1. The algC promoter has partial dependence on the rpoNgene product sigma-54. Moreover, it was shown that AlgR1 binds to two regions of the algC promoter, upstream and downstream of the mRNA start site. Thus, AlgR1 is involved in regulating and modulating alginate gene expression.