Bacillus subtilis F29-3 produces an anti-fungal peptidic antibiotic that is synthesized nonribosomally by fengycin synthetases. Our earlier work established that the promoter of the fengycin synthetase operon is located 86 nucleotides upstream of the translational initiation codon of fenC. This investigation involves transcriptional fusions with a DNA fragment that contains the region between -105 and +80 and determines that deleting the region between -55 and -42 reduces the promoter activity by 64.5%. Transcriptional fusions on the B. subtilis DB2 chromosome also indicate that mutating the sequence markedly reduces the promoter activity. An in vitro transcription analysis confirms that the transcription is inefficient when the sequence in this region is mutated. The electrophoretic mobility shift and footprinting analyses demonstrate that the C-terminal domain of the RNA polymerase subunit binds to the region between -55 and -39. These results indicated that the sequence is an UP element. Finally, this UP element is critical to the production of fengycin, since mutating the UP sequence on the chromosome of B. subtilis F29-3 reduces the transcription of the fen operon by 85% and prevents the cells from producing enough fengycin to suppress the germination of Paecilomyces variotii spores on agar plates.
