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. 2016 Mar 31;7:11062. doi: 10.1038/ncomms11062

Figure 1. E. coli two-plasmid system testing the known direct sigE–sigB interaction of M. tuberculosis.

Figure 1

An E. coli BL21 (DE3) strain was constructed containing a donor plasmid expressing sigE under an IPTG-inducible promoter and a target plasmid carrying a sigB::lacZ reporter fusion. Control strains contained either plasmid with the corresponding empty partner plasmid, or both empty plasmids. Mid-log phase cultures were treated with 100 μM IPTG, and collected before treatment (time 0) and at hourly intervals post treatment. β-galactosidase assays were performed with aliquots of cell lysates using o-nitrophenyl-β-D-galactopyranoside as substrate. Miller units (MU) were calculated as in Methods. Data are presented as mean values (±s.d.) from triplicate experiments. Each colour represents a different strain. pACYCDuet-1, empty donor vector; pJEM13, empty target vector; pACYC::sigE, donor vector expressing IPTG-inducible sigE; pJEM13::sigB, target vector carrying a sigB::lacZ fusion.