FIG. 3.

Effects of the level of OmpRD55E and wild-type OmpR on porin expression in the presence of three different alleles of envZ. Plasmids containing the ompR⁺ or ompRD55E allele were introduced into strains containing the envZ⁺ allele (A), an envZ null allele (B), or the envZ247 allele (C). Cells were grown overnight in LB medium with or without ampicillin (50 μg/ml), subcultured in 20 ml of the same medium, and grown to mid-log phase. The cellular envelopes were isolated as previously described (20). The samples were analyzed by electrophoresis on an SDS–11% polyacrylamide gel containing 4 M urea and identified by staining with Coomassie brilliant blue R-250 (Kodak). The positions of the outer membrane proteins OmpC and OmpF are indicated on the right. The cellular envelopes were prepared from the following strains, which are described in Table 1. Lanes: 1, MC4100; 2, MH1160; 3, pLAN701 in CYL302; 4, pLAN701 in MH1160; 5, pLAN801 in MH1160; 6, pLAN702 in CYL302; 7, pLAN702 in MH1160; 8, pLAN802 in MH1160; 9, MC4100; 10, LM101; 11, pLAN701 in CYL303; 12, pLAN701 in LM101; 13, pLAN801 in LM101; 14, pLAN702 in CYL303; 15, pLAN702 in LM101; 16, pLAN802 in LM101; 17, MC4100; 18, CYL304; 19, pLAN701 in CYL305; 20, pLAN701 in CYL304; 21, pLAN801 in CYL304; 22, pLAN702 in CYL305; 23, pLAN702 in CYL304; 24, pLAN802 in CYL304.