FIG. 2.

Identification of the 5′ end of pvdF transcript. RNA was prepared from P. aeruginosa grown in King's B medium (6) containing the iron chelator ethylenediamine-(o-hydroxy)phenylacetic acid (EDDA) (200 μg/ml) (lanes 1 and 4) or containing FeCl₃ (60 μg/ml) (lanes 2 and 5) and used in primer extension analysis with primers 1 and 2. Lanes 3 and 6, reactions performed without RNA. Sequencing ladders of pvdF DNA obtained with the same oligonucleotides are shown and allowed the precise identification of the 5′ ends of the pvdF transcript. The DNA sequence corresponding to the transcription start site is shown, with the initiating nucleotide in boldface.