FIG. 2.

Analysis of pcl1⁺ promoter sequences required to activate gene expression under basal and iron-replete conditions. (A) Schematic representation of nested 5′ deletions of pcl1⁺ promoter sequences. Nucleotide numbers refer to positions relative to the initiator codon of the pcl1⁺ gene. The gray box represents the wild-type CCAAT sequence, and the hatched box indicates the lacZ gene. (B) Total RNA was isolated from transformants of strain FY435 harboring the indicated pcl1⁺-lacZ promoter derivatives, and steady-state mRNA levels of lacZ and act1⁺ (indicated with arrows) were analyzed by RNase protection experiments. Where indicated, cells were untreated (−) or treated with Dip (250 μM) or FeCl₃ (100 μM). Data illustrated are representative of three independent experiments. (C) The graph indicates the normalized expression levels of pcl1⁺-lacZ mRNA. The values represent averages of three separate determinations ± standard deviations.