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. 2007 Jun 15;3(6):e84. doi: 10.1371/journal.ppat.0030084

Figure 2. Bacterial Two-Hybrid Analysis of Protein–Protein Interactions Involving MglA and SspA.

Figure 2

(A) Schematic representation of the two-hybrid system. Contact between MglA and SspA fused, respectively, to Zif and to the ω subunit of E. coli RNAP activates transcription from the test promoter, driving expression of lacZ. The diagram depicts test promoter placZif1–61, which bears a Zif binding site centered 61 bp upstream of the transcription start site of the lac core promoter (whose −10 and −35 elements are indicated). In E. coli strain KDZif1ΔZ, this test promoter is linked to lacZ on an F′ episome.

(B) Transcription activation by MglA-Zif in the presence of the SspA-ω or MglA-ω fusion proteins, and by SspA-Zif in the presence of the SspA-ω fusion protein. KDZif1ΔZ cells harboring compatible plasmids directing the synthesis of the indicated proteins were grown in the presence of different concentrations of IPTG and assayed for β-galactosidase activity.