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. 2002 Jul;184(13):3640–3648. doi: 10.1128/JB.184.13.3640-3648.2002

FIG. 2.

FIG. 2.

Effect of ibrAB on eib expression in E. coli C lysogens. Lysogen strain numbers are listed in Table 2. (A) Effect of multicopy (m.c.) ibrAB on eib expression in lysogens: lanes 1 and 6, nonlysogenic E. coli C; lanes 2 and 8, P-EibC lysogen; lanes 3 and 10, P-EibD lysogen; lanes 4 and 12, P-EibE lysogen; lanes 5 and 14, P-EibC/D/E triple lysogen. The multicopy ibrAB plasmid pCS7088 was present in the strains shown in lanes 6, 8, 10, 12, and 14 and was absent from those shown in lanes 1 through 5. Lanes 7, 9, 11, and 13 were left empty for clarity. (B) Effect of single-copy (s.c.) (chromosomally inserted) ibrA/B on eib expression in lysogens: lanes 1 and 9, E. coli C; lanes 2 and 10, P-EibB; lanes 3 and 11, P-EibC; lanes 4 and 12, P-EibD; lanes 5 and 13, P-EibE; lanes 6 and 14, P-EibB/D/E triple lysogen; and lanes 7 and 15, P-EibC/D/E triple lysogen. Strains shown in lanes 9 through 15 all had a single copy of ibrAB inserted into the chromosome (Materials and Methods). (C) Comparison of multicopy (mc) and single-copy (sc) ibrAB effects on eib expression. P-EibD lysogens: lane 1, no ibrAB; lane 2, multicopy ibrAB plasmid pCS7088; and lane 3, ibrAB single-copy insertion (CH7140). P-EibE lysogens: lane 4, no ibrAB; lane 5, multicopy ibrAB plasmid pCS7088; and lane 6, ibrAB single-copy insertion (CH7138). (D) Effect of disrupting the ORFs of ibrA and ibrB on eib expression in a P-EibC/D/E triple lysogen (CH6256). Lane 1, no ibrAB; lane 2, intact ibrAB plasmid (pCS7067); lane 3, ibrA disruption (pCS7184); and lane 4, ibrB disruption (pCS7206). For all experiments, whole-cell extracts were fractionated by SDS-PAGE, blotted to polyvinylidene difluoride, and incubated with human IgG Fc-HRP (Materials and Methods). Acrylamide concentrations: 8% (A, B, and C) and 7% (D). Each lane contained approximately 30 μg of protein. Molecular mass units are kilodaltons.