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. 1998 Mar 3;95(5):2691–2696. doi: 10.1073/pnas.95.5.2691

Figure 4.

Figure 4

In vivo interaction between an E. coli HPt domain and the ARR receivers. (A) The structure of plasmids (pIN-ARR-series) by which the ARR receiver domains were moderately expressed in E. coli by using the lpp-lac promoter. (B) An experimental design and the determined β-galactosidase activity in E. coli, showing a possible in vivo interaction between the E. coli HPt domain and the ARR receiver domains. The E. coli strain DZ225 (ΔenvZ, arcB+) carrying an ompC-lacZ fusion was transformed with plasmid pIMA005. This plasmid carries a mutated arcB gene, to express a mutant ArcB sensor kinase (ArcB*). The ArcB* protein has only a functional HPt domain. In E. coli, one can observe a typical His-Asp multistep phosphotransfer signaling pathway, namely, ArcB (transmitter-receiver) to ArcB* (HPt domain) to OmpR (receiver). This particular signal transduction can be monitored by measuring ompC-lacZ expression (β-galactosidase activity) (7, 9). The pIN-ARR series of plasmids were further introduced into these cells and β-galactosidase activities were determined, as indicated in the inset graph. Other details are given in the text.