Transcription of the faoAB operon which encodes the HDT multienzyme complex involved in fatty acid beta-oxidation in Pseudomonas fragi B-0771.

Transcription of the two clustered genes, faoA and faoB, for the multienzyme complex for fatty acid beta-oxidation (HDT) from the Gram-negative bacterium, Pseudomonas fragi, was investigated. Northern blot hybridization and primer extension analysis indicated that these genes comprised an operon, giving a 3.6 kb mRNA. Transcription of the 3.6 kb faoAB mRNA was induced by palmitic acid. Using the lacZ gene as a reporter gene for a promoter activity search, the essential region for induction of the faoAB gene transcription by palmitic acid was mapped at the 331 bp region just upstream of the transcription initiation site. Deletion of the 136 bp SalI-NheI fragment just downstream of the transcription initiation site caused the constitutive expression of the faoA-lacZ fusion protein in P. fragi, suggesting that there is a regulatory element interacting with the transcription repressor.