Figure 5.

Regulation of the isc transcription in response to oxidative stress and in the oxyR mutant. (A) Cultures of NA1000 and ΔiscR strains in PYE medium containing the three transcriptional fusions from Figure 3A in PYE medium were incubated (+) or not (−) with 80 μM H₂O₂ for 30 min (n = 2). (B) Cultures of NA1000 and Δ oxyR strains with the transcriptional fusions were grown in PYE medium up to midlog phase. The cultures were divided in two tubes, containing PYE with no addition (Fe+), or added of 100 μM 2’-2 dipyridil (DPP) (Fe-) and further incubated for 2h (n = 4). (C) Each transcriptional fusion was incubated with 50 μM paraquat (PQ) for 2 h (n = 3). Promoter activity was determined by beta-galactosidase activity assays and expression is shown in Miller units (36). Statistical analysis of significance was calculated using Student’s t-test (p-values are shown above each bar).