Regulation of adhE (encoding ethanol oxidoreductase) by the Fis protein inEscherichia coli

The adhE gene of Escherichia coil encodes a multifunctional ethanol oxidore ductase whose expression is 10-fold higher under anaerobic than aerobic con ditions. Transcription of the gene is under the negative control of the Cra (catabolite repressor-activator) protein, whereas translation of the adhE mRNA requires processing by RNase III. In this report, we show that the exp ression of adhE also depends on the Fis (factor for inversion stimulation) protein. A strain bearing a fis::kan null allele failed to grow anaerobical ly on glucose solely because of inadequate adhE transcription. However, fis expression itself is not under redox control. Sequence inspection of the a dhE promoter revealed three potential Pis binding sites. Electrophoretic mo bility shift analysis, using purified Fis protein and adhE promoter DNA, sh owed three different complexes.