Figure 4.

MrtR inhibits transfer of pAoF64/95 and expression of the tra regulon. The mrtR mutant, NTL4(pAoF64/95ΔmrtR) (a) and the mutant complemented with a cloned wild‐type copy of mrtR (b) were assessed for conjugative transfer when grown in AB minimal medium with mannitol (light gray) or mannopine (dark gray) as the primary source of carbon. The effect of MrtR on expression of the tra regulon was assessed in the complemented mutant, (NTL4[pAoF64/95ΔmrtR, pSRKGm::mrtR]), harboring (c) pRG970b, or (d) the lacZ reporter pRG970b::traC. Strains were grown with or without IPTG to induce expression of MrtR, and assayed for β‐galactosidase activity as described in Experimental Procedures. In all cases, n = 2 and error bars represent standard deviation, except in (b) where 0 and 1 mmol/L IPTG concentrations have an n = 3