Fig 4.
(A) Expression levels of Psyn(hyaA) fused to lacZ in strains containing either bla-Ptac-iscR-FRT-cat-FRT-araC-PBAD-iscS (white bars) or bla-Ptac-iscR(C92A)-FRT-cat-FRT-araC-PBAD-iscS (shaded bars). Cells were grown under anaerobic conditions in MOPS minimal medium containing 20 mM arabinose, tetracycline (10 μg/liter), 0.2% Casamino Acids, and the indicated concentration of IPTG and were assayed for β-galactosidase activity. Error bars for fold repression are given for the data from three strain isolates repeated on at least three independent occasions. (B) Sequence of Psyn(hyaA) promoter fused to lacZ. The IscR binding site from PhyaA (underlined) was incorporated into a construct containing a constitutively active variant of Ptac fused to lacZ. An arrow represents the position of the transcription initiation site.